Add HST/tax support and payment reporting with HST aggregation

Studio Settings gains a default HST rate; the rate is frozen onto each
payment at booking and computed against the pre-tax subtotal, with the
total billed as subtotal + tax. The rate is overridable per booking on
My Lessons while unpaid (recomputing the tax amount), comped
registrations are never taxed, and receipts break out subtotal/HST/total.

Builds the payments report (roadmap #8) from us_payments: a monthly
per-instructor view with subtotal, HST collected, and grand-total
aggregation, plus a nonce-protected CSV export via admin-post. Studio
admins see all instructors and can filter; instructors are scoped to
their own rows. The Payment Report menu is gated on export_payments so
instructors (who lack manage_billing) can reach it.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

README.md

@@ -35,8 +35,8 @@ model, REST API, classes, and tests. For contributor/architecture guidance see
 | Lesson booking (offering → questions → policies) | [lesson-booking.md](docs/features/lesson-booking.md) | ✅ Implemented |
 | Group classes (capacity-enforced enrolment) | [group-classes.md](docs/features/group-classes.md) | ✅ Implemented |
 | Student administration (studio-admin view) | [student-administration.md](docs/features/student-administration.md) | ✅ Implemented |
-| Payments (e-transfer/comp + receipts; Stripe card charge pending) | [payments.md](docs/features/payments.md) | 🟡 Partial |
-| Payment reporting (monthly per-instructor + CSV) | [payment-reporting.md](docs/features/payment-reporting.md) | 🟡 Planned |
+| Payments (e-transfer/comp + receipts + HST; Stripe card charge pending) | [payments.md](docs/features/payments.md) | 🟡 Partial |
+| Payment reporting (monthly per-instructor + HST + CSV) | [payment-reporting.md](docs/features/payment-reporting.md) | ✅ Implemented |
 
 > Payments are deliberately deferred to the end: booking and enrolment ship with a
 > clean seam (a lesson lands `pending`, an enrolment `active`, with `payment_id`

docs/features/payment-reporting.md

@@ -1,49 +1,68 @@
 # Feature: Payment Reporting
 
 ## Overview
-A monthly view of payments per instructor, with a downloadable spreadsheet (CSV) export. The studio admin sees every instructor and can filter; each instructor sees only their own payments. The report is built entirely from `us_payments` — no additional table.
+
+A monthly view of paid payments with **HST aggregation** and a downloadable
+spreadsheet (CSV) export. The studio admin sees every instructor and can filter;
+each instructor sees only their own payments. The report is built entirely from
+`us_payments` — no additional table.
 
 ## Data Source
-Reads `{prefix}us_payments` (see `payments.md`), grouped by calendar month and
-instructor. Each report row joins through to the student and offering for display:
+
+Reads `{prefix}us_payments` (see `payments.md`), filtered to `paid` rows whose
+`paid_at` falls within the selected calendar month, optionally narrowed to one
+instructor. Each report row resolves the student and instructor for display:
 
 | Report Column | Source                                            |
 |---------------|---------------------------------------------------|
-| Date          | `us_payments.paid_at` (falls back to `created_at`) |
+| Date          | `us_payments.paid_at` (date portion)              |
 | Student       | `us_payments.student_id` → display name           |
-| Offering      | registration → `us_offerings.title`               |
+| Instructor    | `us_payments.instructor_id` → display name        |
 | Method        | `us_payments.method`                              |
 | Status        | `us_payments.status`                              |
-| Amount        | `us_payments.amount_cents` / `currency`           |
+| Subtotal      | `us_payments.amount` / `currency`                 |
+| HST           | `us_payments.tax_amount` (with `tax_rate` %)      |
+| Total         | `amount + tax_amount` (`Payment::total()`)        |
 
-Totals are summed over `paid` rows for the selected month.
+Three totals are summed over the selected rows: **subtotal**, **HST collected**
+(the figure the studio remits), and **grand total**.
 
 ## Access Rules
+
 - Studio admin (`view_all_payments`): all instructors; may filter by `instructor_id`.
-- Instructor (`view_own_payments`): rows where `us_payments.instructor_id` is their own user ID only.
+- Instructor (`view_own_payments`): always scoped to their own user ID; the
+  instructor filter is hidden and any requested `instructor_id` is overridden.
 - Export requires `export_payments` and is scoped to the same rows the caller may view.
 
 ## Admin Interface
-**Payments** in wp-admin:
-- Month picker (defaults to the current month) and, for studio admin, an instructor filter
-- A table of payments with a monthly total
-- An **Export** button that downloads the filtered rows as CSV
 
-## REST API
-| Method | Endpoint                                       | Permission           |
-|--------|------------------------------------------------|----------------------|
-| `GET`  | `/wp-json/us-scheduler/v1/payments`            | `view_own_payments` or `view_all_payments` |
-| `GET`  | `/wp-json/us-scheduler/v1/payments/export`     | `export_payments`    |
+**Payment Report** in wp-admin (top-level menu, gated on `export_payments` so
+instructors — who lack `manage_billing` — can reach it):
 
-Query params: `month` (`YYYY-MM`, required), `instructor_id` (optional; ignored for
-instructors, who are always scoped to themselves). `GET /payments/export` returns
-`text/csv` with a `Content-Disposition` attachment header.
+- Month picker (defaults to the current month) and, for studio admin, an
+  instructor filter
+- A summary line of HST collected / subtotal / total collected
+- A table of paid payments with a totals footer
+- An **Export CSV** button that downloads the filtered rows (plus a totals row)
+
+## Export
+
+CSV export is served by an `admin-post.php` handler
+(`admin_post_usc_export_payments`) rather than a REST route, so the browser
+downloads it directly with a nonce-protected link. It honours the same `month`
+and `instructor_id` query params as the page and returns `text/csv` with a
+`Content-Disposition: attachment` header. Instructor requests are scoped to
+their own rows regardless of `instructor_id`.
 
 ## Implementation
-- Report controller: `Unsupervised\Schedular\Payment\PaymentReportController`
-- CSV exporter: `Unsupervised\Schedular\Payment\PaymentExporter`
-- Report query: `Unsupervised\Schedular\Payment\PaymentRepository::report()`
+
+- Report aggregator (pure totals + CSV): `Unsupervised\Schedular\Payment\PaymentReport`
+- Report controller (page + export): `Unsupervised\Schedular\Payment\PaymentReportController`
+- Report query: `Unsupervised\Schedular\Payment\PaymentRepository::findPaidBetween()`
+- Template: `templates/admin/payment-report.php`
+- Menu + `admin_post` wiring: `Unsupervised\Schedular\AdminMenu`
 
 ## Tests
-- `tests/Unit/Payment/PaymentReportControllerTest.php`
-- `tests/Unit/Payment/PaymentExporterTest.php`
+
+- `tests/Unit/Payment/PaymentReportTest.php` — totals and CSV rendering
+- `tests/Unit/Payment/PaymentRepositoryTest.php` — `findPaidBetween` query

docs/features/payments.md

@@ -28,6 +28,22 @@ page (`manage_billing`, studio admin only):
 | `us_stripe_secret_key`       | Stripe secret key                      |
 | `us_stripe_mode`             | `test` or `live`                       |
 | `us_currency`                | Default ISO 4217 currency, e.g. `CAD`  |
+| `us_etransfer_email`         | Studio-default e-transfer destination  |
+| `us_hst_rate`                | Default HST/tax percentage, e.g. `13`  |
+
+## HST / Tax
+
+A studio-default **HST rate** (percentage) is configured on **Studio Settings**
+(`us_hst_rate`, `manage_billing`). At booking the rate is **frozen onto the
+payment** (`us_payments.tax_rate`) and the tax is computed against the pre-tax
+subtotal (`tax_amount = round(amount × rate / 100, 2)`). The billed total is
+`amount + tax_amount` (`Payment::total()`). Comped registrations are never taxed
+(rate and amount are 0).
+
+The rate is overridable **per booking** on **My Lessons** (instructor) while the
+payment is still unpaid; saving recomputes `tax_amount` from the current
+subtotal (`PaymentRepository::updateTax`). Receipts break out subtotal, HST, and
+total when tax applies.
 
 ## Per-Student Billing Method
 Each student's billing method is stored in user meta `us_payment_method`, set by the
@@ -66,6 +82,8 @@ After booking, the destination on a payment can be corrected per booking:
 | `currency`                 | VARCHAR(3)       | ISO 4217, e.g. `CAD`                                  |
 | `method`                   | VARCHAR(20)      | `card` / `etransfer` / `comp`                         |
 | `status`                   | VARCHAR(20)      | `pending` / `paid` / `failed` / `refunded`            |
+| `tax_rate`                 | DECIMAL(5,2)     | HST rate % frozen at booking; editable until paid     |
+| `tax_amount`               | DECIMAL(10,2)    | Computed tax in dollars (`amount × tax_rate / 100`)   |
 | `etransfer_email`          | VARCHAR(191)     | Frozen e-transfer destination; editable until confirmed |
 | `stripe_payment_intent_id` | VARCHAR(255)     | Stripe PaymentIntent id; NULL for e-transfer / comp   |
 | `receipt_number`           | VARCHAR(50)      | Sequential receipt id; set when `paid`                |

src/AdminMenu.php

@@ -17,6 +17,7 @@ use Unsupervised\Schedular\Offering\OfferingController;
 use Unsupervised\Schedular\Offering\OfferingRepository;
 use Unsupervised\Schedular\Payment\BillingMethodResolver;
 use Unsupervised\Schedular\Payment\PaymentController;
+use Unsupervised\Schedular\Payment\PaymentReportController;
 use Unsupervised\Schedular\Payment\PaymentRepository;
 use Unsupervised\Schedular\Payment\PaymentService;
 use Unsupervised\Schedular\Payment\StudioSettings;
@@ -39,22 +40,25 @@ class AdminMenu {
 	private StudentController $studentController;
 	private StudioSettings $settings;
 	private PaymentController $paymentController;
+	private PaymentReportController $paymentReportController;
 
 	public function __construct( AvailabilityRepository $availability, BookingRepository $bookings, OfferingRepository $offerings, QuestionRepository $questions, PolicyRepository $policies, PolicyVersionRepository $policyVersions, PolicyService $policyService, InviteRepository $invites, EnrollmentRepository $enrollments, StudioSettings $settings, PaymentRepository $payments, PaymentService $paymentService, BillingMethodResolver $resolver ) {
-		$this->availabilityController = new AvailabilityController( $availability, $offerings );
-		$this->lessonController       = new LessonController( $bookings, $payments );
-		$this->offeringController     = new OfferingController( $offerings );
-		$this->questionController     = new QuestionController( $questions, $offerings );
-		$this->policyController       = new PolicyController( $policies, $policyVersions, $policyService );
-		$this->registrationController = new RegistrationController( $invites );
-		$this->groupClassController   = new GroupClassController( $enrollments, $offerings );
-		$this->studentController      = new StudentController( $bookings, $availability, $offerings, $enrollments, $resolver );
-		$this->settings               = $settings;
-		$this->paymentController      = new PaymentController( $payments, $paymentService );
+		$this->availabilityController  = new AvailabilityController( $availability, $offerings );
+		$this->lessonController        = new LessonController( $bookings, $payments );
+		$this->offeringController      = new OfferingController( $offerings );
+		$this->questionController      = new QuestionController( $questions, $offerings );
+		$this->policyController        = new PolicyController( $policies, $policyVersions, $policyService );
+		$this->registrationController  = new RegistrationController( $invites );
+		$this->groupClassController    = new GroupClassController( $enrollments, $offerings );
+		$this->studentController       = new StudentController( $bookings, $availability, $offerings, $enrollments, $resolver );
+		$this->settings                = $settings;
+		$this->paymentController       = new PaymentController( $payments, $paymentService );
+		$this->paymentReportController = new PaymentReportController( $payments );
 	}
 
 	public function register(): void {
 		add_action( 'admin_menu', [ $this, 'addPages' ] );
+		add_action( 'admin_post_' . PaymentReportController::EXPORT_ACTION, [ $this->paymentReportController, 'export' ] );
 	}
 
 	public function addPages(): void {
@@ -156,6 +160,18 @@ class AdminMenu {
 			38
 		);
 
+		// Studio admin (all) / instructor (own): monthly payments report with HST.
+		// Gated on export so instructors — who lack manage_billing — can still see it.
+		add_menu_page(
+			__( 'Payment Report', 'unsupervised-schedular' ),
+			__( 'Payment Report', 'unsupervised-schedular' ),
+			RoleManager::CAP_EXPORT_PAYMENTS,
+			'us-reports',
+			[ $this->paymentReportController, 'renderPage' ],
+			'dashicons-chart-bar',
+			39
+		);
+
 		// Studio admin: Stripe credentials and billing settings.
 		add_menu_page(
 			__( 'Studio Settings', 'unsupervised-schedular' ),
@@ -164,7 +180,7 @@ class AdminMenu {
 			'us-settings',
 			[ $this->settings, 'renderPage' ],
 			'dashicons-admin-settings',
-			39
+			40
 		);
 
 		// Instructor: view their upcoming lessons.

src/Booking/LessonController.php

@@ -39,8 +39,8 @@ class LessonController {
 	}
 
 	/**
-	 * Handle a per-lesson e-transfer email override. When $onlyOwn, the payment
-	 * must belong to the current instructor.
+	 * Handle a per-lesson payment override (e-transfer email or HST rate). When
+	 * $onlyOwn, the payment must belong to the current instructor.
 	 */
 	private function handleEtransferUpdate( bool $onlyOwn ): void {
 		if ( ! isset( $_POST['usc_action'] ) || ! check_admin_referer( 'usc_lesson_action' ) ) {
@@ -48,26 +48,32 @@ class LessonController {
 		}
 
 		// phpcs:disable WordPress.Security.NonceVerification.Missing -- nonce checked above.
-		if ( 'set_etransfer' !== sanitize_key( wp_unslash( $_POST['usc_action'] ?? '' ) ) ) {
-			return;
-		}
-
+		$action    = sanitize_key( wp_unslash( $_POST['usc_action'] ?? '' ) );
 		$paymentId = absint( $_POST['payment_id'] ?? 0 );
 		$email     = sanitize_email( wp_unslash( $_POST['etransfer_email'] ?? '' ) );
+		$taxRate   = isset( $_POST['tax_rate'] ) ? max( 0.0, (float) $_POST['tax_rate'] ) : 0.0;
 		// phpcs:enable WordPress.Security.NonceVerification.Missing
 
-		if ( $paymentId <= 0 ) {
+		if ( $paymentId <= 0 || ! in_array( $action, [ 'set_etransfer', 'set_tax' ], true ) ) {
 			return;
 		}
 
 		$payment = $this->payments->findById( $paymentId );
-		if ( null !== $payment && ( ! $onlyOwn || get_current_user_id() === $payment->instructorId ) ) {
-			$this->payments->updateEtransferEmail( $paymentId, '' !== $email ? $email : null );
+		if ( null === $payment || ( $onlyOwn && get_current_user_id() !== $payment->instructorId ) ) {
+			return;
 		}
+
+		if ( 'set_tax' === $action ) {
+			$this->payments->updateTax( $paymentId, $taxRate );
+			return;
+		}
+
+		$this->payments->updateEtransferEmail( $paymentId, '' !== $email ? $email : null );
 	}
 
 	/**
-	 * Build a display row for a lesson, including its e-transfer payment override.
+	 * Build a display row for a lesson, including its e-transfer and HST payment
+	 * overrides.
 	 *
 	 * @return array<string, mixed>
 	 */
@@ -83,8 +89,14 @@ class LessonController {
 			'status'             => $lesson->status,
 			'notes'              => $lesson->notes ?? '',
 			'payment_id'         => $payment ? (int) $payment->id : 0,
+			'currency'           => $payment ? (string) $payment->currency : '',
+			'amount'             => $payment ? (float) $payment->amount : 0.0,
+			'tax_rate'           => $payment ? (float) $payment->taxRate : 0.0,
+			'tax_amount'         => $payment ? (float) $payment->taxAmount : 0.0,
+			'total'              => $payment ? $payment->total() : 0.0,
 			'etransfer_email'    => $payment ? (string) $payment->etransferEmail : '',
 			'etransfer_editable' => null !== $payment && Payment::METHOD_ETRANSFER === $payment->method && ! $payment->isPaid(),
+			'tax_editable'       => null !== $payment && ! $payment->isPaid(),
 		];
 	}
 }

src/Payment/Payment.php

@@ -40,6 +40,8 @@ class Payment {
 		public readonly string $currency = 'CAD',
 		public readonly string $method = self::METHOD_ETRANSFER,
 		public readonly string $status = self::STATUS_PENDING,
+		public readonly float $taxRate = 0.0,
+		public readonly float $taxAmount = 0.0,
 		public readonly ?string $etransferEmail = null,
 		public readonly ?string $stripePaymentIntentId = null,
 		public readonly ?string $receiptNumber = null,
@@ -58,6 +60,8 @@ class Payment {
 			currency:              $row->currency,
 			method:                $row->method,
 			status:                $row->status,
+			taxRate:               (float) $row->tax_rate,
+			taxAmount:             (float) $row->tax_amount,
 			etransferEmail:        $row->etransfer_email,
 			stripePaymentIntentId: $row->stripe_payment_intent_id,
 			receiptNumber:         $row->receipt_number,
@@ -71,6 +75,13 @@ class Payment {
 		return self::STATUS_PAID === $this->status;
 	}
 
+	/**
+	 * Amount billed including tax.
+	 */
+	public function total(): float {
+		return round( $this->amount + $this->taxAmount, 2 );
+	}
+
 	/**
 	 * Returns a plain array representation of the payment.
 	 *
@@ -85,6 +96,9 @@ class Payment {
 			'etransfer_email'   => $this->etransferEmail,
 			'registration_id'   => $this->registrationId,
 			'amount'            => $this->amount,
+			'tax_rate'          => $this->taxRate,
+			'tax_amount'        => $this->taxAmount,
+			'total'             => $this->total(),
 			'currency'          => $this->currency,
 			'method'            => $this->method,
 			'status'            => $this->status,

src/Payment/PaymentReport.php

@@ -0,0 +1,105 @@
+<?php
+declare(strict_types=1);
+
+namespace Unsupervised\Schedular\Payment;
+
+/**
+ * Pure aggregator over a set of paid-payment display rows: produces the column
+ * totals (subtotal, HST collected, grand total) and a CSV rendering. Building
+ * the rows (name lookups, filtering) is the controller's job — this class does
+ * no I/O so it stays trivially testable.
+ */
+class PaymentReport {
+
+	/**
+	 * Build a report over already-resolved display rows.
+	 *
+	 * @param list<array{date: string, student: string, instructor: string, method: string, status: string, amount: float, tax_rate: float, tax_amount: float, total: float}> $rows
+	 */
+	public function __construct( private array $rows ) {}
+
+	/**
+	 * The report's display rows.
+	 *
+	 * @return list<array{date: string, student: string, instructor: string, method: string, status: string, amount: float, tax_rate: float, tax_amount: float, total: float}>
+	 */
+	public function rows(): array {
+		return $this->rows;
+	}
+
+	public function count(): int {
+		return count( $this->rows );
+	}
+
+	public function totalAmount(): float {
+		return round( array_sum( array_column( $this->rows, 'amount' ) ), 2 );
+	}
+
+	/**
+	 * Total HST collected across all rows — the figure the studio remits.
+	 */
+	public function totalTax(): float {
+		return round( array_sum( array_column( $this->rows, 'tax_amount' ) ), 2 );
+	}
+
+	public function grandTotal(): float {
+		return round( array_sum( array_column( $this->rows, 'total' ) ), 2 );
+	}
+
+	/**
+	 * Render the report as CSV, including a trailing totals row.
+	 */
+	public function toCsv(): string {
+		$lines = [];
+
+		$lines[] = $this->csvLine(
+			[ 'Date', 'Student', 'Instructor', 'Method', 'Status', 'Subtotal', 'HST Rate', 'HST', 'Total' ]
+		);
+
+		foreach ( $this->rows as $row ) {
+			$lines[] = $this->csvLine(
+				[
+					$row['date'],
+					$row['student'],
+					$row['instructor'],
+					$row['method'],
+					$row['status'],
+					number_format( $row['amount'], 2, '.', '' ),
+					number_format( $row['tax_rate'], 2, '.', '' ),
+					number_format( $row['tax_amount'], 2, '.', '' ),
+					number_format( $row['total'], 2, '.', '' ),
+				]
+			);
+		}
+
+		$lines[] = $this->csvLine(
+			[
+				'Totals',
+				'',
+				'',
+				'',
+				'',
+				number_format( $this->totalAmount(), 2, '.', '' ),
+				'',
+				number_format( $this->totalTax(), 2, '.', '' ),
+				number_format( $this->grandTotal(), 2, '.', '' ),
+			]
+		);
+
+		return implode( "\n", $lines ) . "\n";
+	}
+
+	/**
+	 * Format one CSV record, quoting fields and escaping embedded quotes.
+	 *
+	 * @param list<string> $fields
+	 */
+	private function csvLine( array $fields ): string {
+		$escaped = array_map(
+			static fn( string $field ): string => '"' . str_replace( '"', '""', $field ) . '"',
+			$fields
+		);
+
+		return implode( ',', $escaped );
+	}
+}

src/Payment/PaymentReportController.php

@@ -0,0 +1,130 @@
+<?php
+declare(strict_types=1);
+
+namespace Unsupervised\Schedular\Payment;
+
+use Unsupervised\Schedular\Auth\RoleManager;
+
+class PaymentReportController {
+
+	public const EXPORT_ACTION = 'usc_export_payments';
+
+	public function __construct( private PaymentRepository $payments ) {}
+
+	/**
+	 * Render the monthly payments report with HST aggregation. Studio admins see
+	 * all instructors; instructors are scoped to their own payments.
+	 */
+	public function renderPage(): void {
+		if ( ! current_user_can( RoleManager::CAP_VIEW_ALL_PAYMENTS ) && ! current_user_can( RoleManager::CAP_VIEW_OWN_PAYMENTS ) ) {
+			wp_die( esc_html__( 'You do not have permission to view payment reports.', 'unsupervised-schedular' ) );
+		}
+
+		// phpcs:disable WordPress.Security.NonceVerification.Recommended -- read-only report filters, no state change.
+		$month        = $this->sanitizeMonth( isset( $_GET['month'] ) ? sanitize_text_field( wp_unslash( $_GET['month'] ) ) : '' );
+		$instructorId = isset( $_GET['instructor_id'] ) ? absint( $_GET['instructor_id'] ) : 0;
+		// phpcs:enable WordPress.Security.NonceVerification.Recommended
+
+		$instructorId = $this->scopeInstructor( $instructorId );
+
+		$report    = $this->buildReport( $month, $instructorId );
+		$canExport = current_user_can( RoleManager::CAP_EXPORT_PAYMENTS );
+		$canFilter = current_user_can( RoleManager::CAP_VIEW_ALL_PAYMENTS );
+		$exportUrl = wp_nonce_url(
+			admin_url( 'admin-post.php?action=' . self::EXPORT_ACTION . '&month=' . rawurlencode( $month ) . '&instructor_id=' . $instructorId ),
+			self::EXPORT_ACTION
+		);
+
+		$instructors = $canFilter
+			? get_users(
+				[
+					'role'   => RoleManager::INSTRUCTOR,
+					'fields' => [ 'ID', 'display_name' ],
+				]
+			)
+			: [];
+
+		include USC_PLUGIN_DIR . 'templates/admin/payment-report.php';
+	}
+
+	/**
+	 * Stream the report as a CSV download (admin_post handler).
+	 */
+	public function export(): void {
+		if ( ! current_user_can( RoleManager::CAP_EXPORT_PAYMENTS ) ) {
+			wp_die( esc_html__( 'You do not have permission to export payments.', 'unsupervised-schedular' ) );
+		}
+
+		check_admin_referer( self::EXPORT_ACTION );
+
+		// phpcs:disable WordPress.Security.NonceVerification.Recommended -- nonce checked above.
+		$month        = $this->sanitizeMonth( isset( $_GET['month'] ) ? sanitize_text_field( wp_unslash( $_GET['month'] ) ) : '' );
+		$instructorId = isset( $_GET['instructor_id'] ) ? absint( $_GET['instructor_id'] ) : 0;
+		// phpcs:enable WordPress.Security.NonceVerification.Recommended
+
+		$instructorId = $this->scopeInstructor( $instructorId );
+		$report       = $this->buildReport( $month, $instructorId );
+
+		$filename = 'payments-' . $month . '.csv';
+		header( 'Content-Type: text/csv; charset=utf-8' );
+		header( 'Content-Disposition: attachment; filename="' . $filename . '"' );
+
+		echo $report->toCsv(); // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- CSV body, not HTML.
+
+		exit;
+	}
+
+	/**
+	 * Restrict the requested instructor to the current user when they may only
+	 * see their own payments.
+	 */
+	private function scopeInstructor( int $instructorId ): int {
+		if ( ! current_user_can( RoleManager::CAP_VIEW_ALL_PAYMENTS ) ) {
+			return get_current_user_id();
+		}
+
+		return $instructorId;
+	}
+
+	/**
+	 * Build a report of paid payments for the given `Y-m` month, optionally for
+	 * one instructor.
+	 */
+	private function buildReport( string $month, int $instructorId ): PaymentReport {
+		$start = $month . '-01 00:00:00';
+		$end   = gmdate( 'Y-m-d H:i:s', strtotime( $month . '-01 00:00:00 +1 month' ) );
+
+		$rows = array_map(
+			static function ( Payment $payment ): array {
+				$student    = get_userdata( $payment->studentId );
+				$instructor = get_userdata( $payment->instructorId );
+
+				return [
+					'date'       => substr( (string) $payment->paidAt, 0, 10 ),
+					'student'    => $student ? $student->display_name : (string) $payment->studentId,
+					'instructor' => $instructor ? $instructor->display_name : (string) $payment->instructorId,
+					'method'     => $payment->method,
+					'status'     => $payment->status,
+					'amount'     => (float) $payment->amount,
+					'tax_rate'   => (float) $payment->taxRate,
+					'tax_amount' => (float) $payment->taxAmount,
+					'total'      => $payment->total(),
+				];
+			},
+			$this->payments->findPaidBetween( $start, $end, $instructorId )
+		);
+
+		return new PaymentReport( $rows );
+	}
+
+	/**
+	 * Validate a `Y-m` month string, defaulting to the current month.
+	 */
+	private function sanitizeMonth( string $month ): string {
+		if ( 1 === preg_match( '/^\d{4}-\d{2}$/', $month ) ) {
+			return $month;
+		}
+
+		return gmdate( 'Y-m' );
+	}
+}

src/Payment/PaymentRepository.php

@@ -23,6 +23,8 @@ class PaymentRepository {
 				'currency'                 => $payment->currency,
 				'method'                   => $payment->method,
 				'status'                   => $payment->status,
+				'tax_rate'                 => $payment->taxRate,
+				'tax_amount'               => $payment->taxAmount,
 				'etransfer_email'          => $payment->etransferEmail,
 				'stripe_payment_intent_id' => $payment->stripePaymentIntentId,
 				'receipt_number'           => $payment->receiptNumber,
@@ -30,7 +32,7 @@ class PaymentRepository {
 				'paid_at'                  => $payment->paidAt,
 				'created_at'               => current_time( 'mysql' ),
 			],
-			[ '%d', '%d', '%s', '%d', '%f', '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s' ]
+			[ '%d', '%d', '%s', '%d', '%f', '%s', '%s', '%s', '%f', '%f', '%s', '%s', '%s', '%s', '%s', '%s' ]
 		);
 
 		return $this->db->insert_id;
@@ -46,6 +48,42 @@ class PaymentRepository {
 		);
 	}
 
+	/**
+	 * Set a payment's tax rate and recompute the tax amount from its subtotal.
+	 */
+	public function updateTax( int $id, float $rate ): bool {
+		return false !== $this->db->query(
+			$this->db->prepare(
+				"UPDATE {$this->table} SET tax_rate = %f, tax_amount = ROUND( amount * %f / 100, 2 ) WHERE id = %d",
+				$rate,
+				$rate,
+				$id
+			)
+		);
+	}
+
+	/**
+	 * Paid payments in a month (`Y-m` bounds), optionally for one instructor —
+	 * the reporting source.
+	 *
+	 * @return list<Payment>
+	 */
+	public function findPaidBetween( string $from, string $to, int $instructorId = 0 ): array {
+		$sql    = "SELECT * FROM {$this->table} WHERE status = %s AND paid_at >= %s AND paid_at < %s";
+		$params = [ Payment::STATUS_PAID, $from, $to ];
+
+		if ( $instructorId > 0 ) {
+			$sql     .= ' AND instructor_id = %d';
+			$params[] = $instructorId;
+		}
+
+		$sql .= ' ORDER BY paid_at ASC';
+
+		$rows = $this->db->get_results( $this->db->prepare( $sql, $params ) );
+
+		return array_map( Payment::fromRow( ... ), $rows ?? [] );
+	}
+
 	public function findById( int $id ): ?Payment {
 		$row = $this->db->get_row(
 			$this->db->prepare( "SELECT * FROM {$this->table} WHERE id = %d", $id )

src/Payment/PaymentService.php

@@ -41,6 +41,10 @@ class PaymentService {
 			? $offeringEtransferEmail
 			: ( '' !== $this->settings->etransferEmail() ? $this->settings->etransferEmail() : null );
 
+		// HST is frozen from the studio default at booking; comped students are not taxed.
+		$taxRate   = Payment::METHOD_COMP === $method ? 0.0 : $this->settings->hstRate();
+		$taxAmount = round( $amount * $taxRate / 100, 2 );
+
 		$id = $this->payments->insert(
 			new Payment(
 				studentId:        $studentId,
@@ -51,6 +55,8 @@ class PaymentService {
 				currency:         $currency,
 				method:           $method,
 				status:           $status,
+				taxRate:          $taxRate,
+				taxAmount:        $taxAmount,
 				etransferEmail:   $etransferEmail,
 			)
 		);

src/Payment/ReceiptMailer.php

@@ -20,13 +20,26 @@ class ReceiptMailer {
 			(string) $payment->receiptNumber
 		);
 
-		$body = sprintf(
-			/* translators: 1: amount, 2: currency, 3: receipt number */
-			__( "Thank you. We have recorded your payment of %1\$s %2\$s.\n\nReceipt: %3\$s", 'unsupervised-schedular' ),
-			number_format( $payment->amount, 2 ),
-			$payment->currency,
-			(string) $payment->receiptNumber
-		);
+		if ( $payment->taxAmount > 0 ) {
+			$body = sprintf(
+				/* translators: 1: currency, 2: subtotal, 3: HST rate, 4: HST amount, 5: total, 6: receipt number */
+				__( "Thank you. We have recorded your payment.\n\nSubtotal: %1\$s %2\$s\nHST (%3\$s%%): %1\$s %4\$s\nTotal: %1\$s %5\$s\n\nReceipt: %6\$s", 'unsupervised-schedular' ),
+				$payment->currency,
+				number_format( $payment->amount, 2 ),
+				number_format( $payment->taxRate, 2 ),
+				number_format( $payment->taxAmount, 2 ),
+				number_format( $payment->total(), 2 ),
+				(string) $payment->receiptNumber
+			);
+		} else {
+			$body = sprintf(
+				/* translators: 1: amount, 2: currency, 3: receipt number */
+				__( "Thank you. We have recorded your payment of %1\$s %2\$s.\n\nReceipt: %3\$s", 'unsupervised-schedular' ),
+				number_format( $payment->total(), 2 ),
+				$payment->currency,
+				(string) $payment->receiptNumber
+			);
+		}
 
 		return (bool) wp_mail( $student->user_email, $subject, $body );
 	}

src/Payment/StudioSettings.php

@@ -12,6 +12,7 @@ class StudioSettings {
 	public const OPT_MODE            = 'us_stripe_mode';
 	public const OPT_CURRENCY        = 'us_currency';
 	public const OPT_ETRANSFER_EMAIL = 'us_etransfer_email';
+	public const OPT_HST_RATE        = 'us_hst_rate';
 
 	public function publishableKey(): string {
 		return (string) get_option( self::OPT_PUBLISHABLE, '' );
@@ -39,6 +40,13 @@ class StudioSettings {
 		return (string) get_option( self::OPT_ETRANSFER_EMAIL, '' );
 	}
 
+	/**
+	 * Default HST/tax rate as a percentage (e.g. 13.0). 0 means no tax.
+	 */
+	public function hstRate(): float {
+		return max( 0.0, (float) get_option( self::OPT_HST_RATE, 0 ) );
+	}
+
 	/**
 	 * Whether Stripe is configured. When false the platform falls back to
 	 * e-transfer billing and card processing is unavailable.
@@ -61,6 +69,7 @@ class StudioSettings {
 		$mode             = $this->mode();
 		$currency         = $this->currency();
 		$etransferEmail   = $this->etransferEmail();
+		$hstRate          = $this->hstRate();
 		$stripeConfigured = $this->isStripeConfigured();
 
 		include USC_PLUGIN_DIR . 'templates/admin/settings.php';
@@ -75,6 +84,8 @@ class StudioSettings {
 		update_option( self::OPT_MODE, 'live' === $mode ? 'live' : 'test' );
 		update_option( self::OPT_CURRENCY, strtoupper( sanitize_text_field( wp_unslash( $_POST['currency'] ?? 'CAD' ) ) ) );
 		update_option( self::OPT_ETRANSFER_EMAIL, sanitize_email( wp_unslash( $_POST['etransfer_email'] ?? '' ) ) );
+		$hstRate = isset( $_POST['hst_rate'] ) ? (float) $_POST['hst_rate'] : 0.0;
+		update_option( self::OPT_HST_RATE, max( 0.0, $hstRate ) );
 		// phpcs:enable WordPress.Security.NonceVerification.Missing
 	}
 }

src/Schema.php

@@ -151,6 +151,8 @@ class Schema {
                 currency                 VARCHAR(3)      NOT NULL DEFAULT 'CAD',
                 method                   VARCHAR(20)     NOT NULL DEFAULT 'etransfer',
                 status                   VARCHAR(20)     NOT NULL DEFAULT 'pending',
+                tax_rate                 DECIMAL(5,2)    NOT NULL DEFAULT 0,
+                tax_amount               DECIMAL(10,2)   NOT NULL DEFAULT 0,
                 etransfer_email          VARCHAR(191)    DEFAULT NULL,
                 stripe_payment_intent_id VARCHAR(255)    DEFAULT NULL,
                 receipt_number           VARCHAR(50)     DEFAULT NULL,

templates/admin/lessons.php

@@ -5,7 +5,7 @@ if (! defined('ABSPATH')) {
     exit;
 }
 
-/** @var list<array{student: string, instructor: string, slot_id: int, status: string, notes: string, payment_id: int, etransfer_email: string, etransfer_editable: bool}> $rows */
+/** @var list<array{student: string, instructor: string, slot_id: int, status: string, notes: string, payment_id: int, currency: string, amount: float, tax_rate: float, tax_amount: float, total: float, etransfer_email: string, etransfer_editable: bool, tax_editable: bool}> $rows */
 ?>
 <div class="wrap">
     <h1><?php esc_html_e('Lessons', 'unsupervised-schedular'); ?></h1>
@@ -20,6 +20,8 @@ if (! defined('ABSPATH')) {
                     <th><?php esc_html_e('Instructor', 'unsupervised-schedular'); ?></th>
                     <th><?php esc_html_e('Slot ID', 'unsupervised-schedular'); ?></th>
                     <th><?php esc_html_e('Status', 'unsupervised-schedular'); ?></th>
+                    <th><?php esc_html_e('HST', 'unsupervised-schedular'); ?></th>
+                    <th><?php esc_html_e('Total', 'unsupervised-schedular'); ?></th>
                     <th><?php esc_html_e('E-transfer email', 'unsupervised-schedular'); ?></th>
                     <th><?php esc_html_e('Notes', 'unsupervised-schedular'); ?></th>
                 </tr>
@@ -31,6 +33,21 @@ if (! defined('ABSPATH')) {
                         <td><?php echo esc_html($row['instructor']); ?></td>
                         <td><?php echo esc_html((string) $row['slot_id']); ?></td>
                         <td><?php echo esc_html($row['status']); ?></td>
+                        <td>
+                            <?php if ($row['tax_editable']) : ?>
+                                <form method="post" style="display:flex; gap:4px; align-items:center;">
+                                    <?php wp_nonce_field('usc_lesson_action'); ?>
+                                    <input type="hidden" name="usc_action" value="set_tax">
+                                    <input type="hidden" name="payment_id" value="<?php echo esc_attr((string) $row['payment_id']); ?>">
+                                    <input type="number" name="tax_rate" min="0" max="100" step="0.01" style="width:5em;" value="<?php echo esc_attr(number_format($row['tax_rate'], 2)); ?>">
+                                    <span>%</span>
+                                    <button type="submit" class="button button-small"><?php esc_html_e('Save', 'unsupervised-schedular'); ?></button>
+                                </form>
+                            <?php else : ?>
+                                <?php echo esc_html(number_format($row['tax_rate'], 2) . '% (' . $row['currency'] . ' ' . number_format($row['tax_amount'], 2) . ')'); ?>
+                            <?php endif; ?>
+                        </td>
+                        <td><?php echo $row['payment_id'] > 0 ? esc_html($row['currency'] . ' ' . number_format($row['total'], 2)) : esc_html('—'); ?></td>
                         <td>
                             <?php if ($row['etransfer_editable']) : ?>
                                 <form method="post" style="display:flex; gap:4px;">

templates/admin/payment-report.php

@@ -0,0 +1,99 @@
+<?php
+declare(strict_types=1);
+
+if (! defined('ABSPATH')) {
+    exit;
+}
+
+use Unsupervised\Schedular\Payment\PaymentReport;
+
+/**
+ * @var PaymentReport $report
+ * @var string $month
+ * @var int $instructorId
+ * @var bool $canExport
+ * @var bool $canFilter
+ * @var string $exportUrl
+ * @var list<\WP_User|\stdClass> $instructors
+ */
+?>
+<div class="wrap">
+    <h1><?php esc_html_e('Payment Report', 'unsupervised-schedular'); ?></h1>
+
+    <form method="get" style="margin: 1em 0; display:flex; gap:8px; align-items:flex-end; flex-wrap:wrap;">
+        <input type="hidden" name="page" value="us-reports">
+        <label>
+            <?php esc_html_e('Month', 'unsupervised-schedular'); ?><br>
+            <input type="month" name="month" value="<?php echo esc_attr($month); ?>">
+        </label>
+        <?php if ($canFilter) : ?>
+            <label>
+                <?php esc_html_e('Instructor', 'unsupervised-schedular'); ?><br>
+                <select name="instructor_id">
+                    <option value="0"><?php esc_html_e('All instructors', 'unsupervised-schedular'); ?></option>
+                    <?php foreach ($instructors as $instructor) : ?>
+                        <option value="<?php echo esc_attr((string) $instructor->ID); ?>" <?php selected($instructorId, (int) $instructor->ID); ?>>
+                            <?php echo esc_html($instructor->display_name); ?>
+                        </option>
+                    <?php endforeach; ?>
+                </select>
+            </label>
+        <?php endif; ?>
+        <button type="submit" class="button"><?php esc_html_e('Filter', 'unsupervised-schedular'); ?></button>
+        <?php if ($canExport) : ?>
+            <a class="button button-secondary" href="<?php echo esc_url($exportUrl); ?>"><?php esc_html_e('Export CSV', 'unsupervised-schedular'); ?></a>
+        <?php endif; ?>
+    </form>
+
+    <p>
+        <strong><?php esc_html_e('HST collected:', 'unsupervised-schedular'); ?></strong>
+        <?php echo esc_html(number_format($report->totalTax(), 2)); ?>
+        &nbsp;|&nbsp;
+        <strong><?php esc_html_e('Subtotal:', 'unsupervised-schedular'); ?></strong>
+        <?php echo esc_html(number_format($report->totalAmount(), 2)); ?>
+        &nbsp;|&nbsp;
+        <strong><?php esc_html_e('Total collected:', 'unsupervised-schedular'); ?></strong>
+        <?php echo esc_html(number_format($report->grandTotal(), 2)); ?>
+    </p>
+
+    <?php if (0 === $report->count()) : ?>
+        <p><?php esc_html_e('No paid payments in this period.', 'unsupervised-schedular'); ?></p>
+    <?php else : ?>
+        <table class="wp-list-table widefat fixed striped">
+            <thead>
+                <tr>
+                    <th><?php esc_html_e('Date', 'unsupervised-schedular'); ?></th>
+                    <th><?php esc_html_e('Student', 'unsupervised-schedular'); ?></th>
+                    <th><?php esc_html_e('Instructor', 'unsupervised-schedular'); ?></th>
+                    <th><?php esc_html_e('Method', 'unsupervised-schedular'); ?></th>
+                    <th><?php esc_html_e('Status', 'unsupervised-schedular'); ?></th>
+                    <th><?php esc_html_e('Subtotal', 'unsupervised-schedular'); ?></th>
+                    <th><?php esc_html_e('HST', 'unsupervised-schedular'); ?></th>
+                    <th><?php esc_html_e('Total', 'unsupervised-schedular'); ?></th>
+                </tr>
+            </thead>
+            <tbody>
+                <?php foreach ($report->rows() as $row) : ?>
+                    <tr>
+                        <td><?php echo esc_html($row['date']); ?></td>
+                        <td><?php echo esc_html($row['student']); ?></td>
+                        <td><?php echo esc_html($row['instructor']); ?></td>
+                        <td><?php echo esc_html($row['method']); ?></td>
+                        <td><?php echo esc_html($row['status']); ?></td>
+                        <td><?php echo esc_html(number_format($row['amount'], 2)); ?></td>
+                        <td><?php echo esc_html(number_format($row['tax_amount'], 2) . ' (' . number_format($row['tax_rate'], 2) . '%)'); ?></td>
+                        <td><?php echo esc_html(number_format($row['total'], 2)); ?></td>
+                    </tr>
+                <?php endforeach; ?>
+            </tbody>
+            <tfoot>
+                <tr>
+                    <th colspan="5"><?php esc_html_e('Totals', 'unsupervised-schedular'); ?></th>
+                    <th><?php echo esc_html(number_format($report->totalAmount(), 2)); ?></th>
+                    <th><?php echo esc_html(number_format($report->totalTax(), 2)); ?></th>
+                    <th><?php echo esc_html(number_format($report->grandTotal(), 2)); ?></th>
+                </tr>
+            </tfoot>
+        </table>
+    <?php endif; ?>
+</div>

templates/admin/settings.php

@@ -11,6 +11,7 @@ if (! defined('ABSPATH')) {
  * @var string $mode
  * @var string $currency
  * @var string $etransferEmail
+ * @var float  $hstRate
  * @var bool   $stripeConfigured
  */
 ?>
@@ -53,6 +54,13 @@ if (! defined('ABSPATH')) {
                 <th><label for="currency"><?php esc_html_e('Default currency', 'unsupervised-schedular'); ?></label></th>
                 <td><input type="text" name="currency" id="currency" class="small-text" maxlength="3" value="<?php echo esc_attr($currency); ?>"></td>
             </tr>
+            <tr>
+                <th><label for="hst_rate"><?php esc_html_e('Default HST rate (%)', 'unsupervised-schedular'); ?></label></th>
+                <td>
+                    <input type="number" name="hst_rate" id="hst_rate" class="small-text" min="0" max="100" step="0.01" value="<?php echo esc_attr(number_format($hstRate, 2)); ?>">
+                    <p class="description"><?php esc_html_e('Added to the subtotal when billing. 0 means no tax. Overridable per booking on My Lessons.', 'unsupervised-schedular'); ?></p>
+                </td>
+            </tr>
         </table>
 
         <h2><?php esc_html_e('E-transfer', 'unsupervised-schedular'); ?></h2>

tests/Unit/Payment/PaymentReportTest.php

@@ -0,0 +1,83 @@
+<?php
+declare(strict_types=1);
+
+namespace Unsupervised\Schedular\Tests\Unit\Payment;
+
+use Unsupervised\Schedular\Payment\PaymentReport;
+use Unsupervised\Schedular\Tests\Unit\TestCase;
+
+class PaymentReportTest extends TestCase
+{
+    /**
+     * @return list<array{date: string, student: string, instructor: string, method: string, status: string, amount: float, tax_rate: float, tax_amount: float, total: float}>
+     */
+    private function rows(): array
+    {
+        return [
+            [
+                'date'       => '2026-06-02',
+                'student'    => 'Ada',
+                'instructor' => 'Pat',
+                'method'     => 'etransfer',
+                'status'     => 'paid',
+                'amount'     => 100.00,
+                'tax_rate'   => 13.0,
+                'tax_amount' => 13.00,
+                'total'      => 113.00,
+            ],
+            [
+                'date'       => '2026-06-09',
+                'student'    => 'Grace',
+                'instructor' => 'Pat',
+                'method'     => 'card',
+                'status'     => 'paid',
+                'amount'     => 50.00,
+                'tax_rate'   => 13.0,
+                'tax_amount' => 6.50,
+                'total'      => 56.50,
+            ],
+        ];
+    }
+
+    public function testTotalsAggregateAmountsAndTax(): void
+    {
+        $report = new PaymentReport($this->rows());
+
+        self::assertSame(2, $report->count());
+        self::assertSame(150.00, $report->totalAmount());
+        self::assertSame(19.50, $report->totalTax());
+        self::assertSame(169.50, $report->grandTotal());
+    }
+
+    public function testEmptyReportHasZeroTotals(): void
+    {
+        $report = new PaymentReport([]);
+
+        self::assertSame(0, $report->count());
+        self::assertSame(0.0, $report->totalTax());
+        self::assertSame(0.0, $report->grandTotal());
+    }
+
+    public function testCsvIncludesHeaderRowsAndTotals(): void
+    {
+        $csv   = (new PaymentReport($this->rows()))->toCsv();
+        $lines = explode("\n", trim($csv));
+
+        // header + 2 data rows + totals row.
+        self::assertCount(4, $lines);
+        self::assertStringContainsString('"Date","Student","Instructor"', $lines[0]);
+        self::assertStringContainsString('"Ada"', $lines[1]);
+        self::assertStringContainsString('"Totals"', $lines[3]);
+        self::assertStringContainsString('"19.50"', $lines[3]);
+        self::assertStringContainsString('"169.50"', $lines[3]);
+    }
+
+    public function testCsvEscapesEmbeddedQuotes(): void
+    {
+        $rows    = $this->rows();
+        $rows[0]['student'] = 'Ada "The Great"';
+        $csv     = (new PaymentReport($rows))->toCsv();
+
+        self::assertStringContainsString('"Ada ""The Great"""', $csv);
+    }
+}

tests/Unit/Payment/PaymentRepositoryTest.php

@@ -62,6 +62,42 @@ class PaymentRepositoryTest extends TestCase
         self::assertTrue($this->repo->markPaid(50, 'USC-50'));
     }
 
+    public function testUpdateTaxRecomputesAmountFromRate(): void
+    {
+        $this->db->shouldReceive('prepare')
+            ->once()
+            ->with(Mockery::pattern('/tax_amount = ROUND\( amount \* %f \/ 100, 2 \)/'), 13.0, 13.0, 50)
+            ->andReturn('UPDATE ...');
+
+        $this->db->shouldReceive('query')->once()->with('UPDATE ...')->andReturn(1);
+
+        self::assertTrue($this->repo->updateTax(50, 13.0));
+    }
+
+    public function testFindPaidBetweenFiltersByInstructor(): void
+    {
+        $this->db->shouldReceive('prepare')
+            ->once()
+            ->with(Mockery::pattern('/status = %s AND paid_at >= %s AND paid_at < %s AND instructor_id = %d/'), ['paid', '2026-06-01 00:00:00', '2026-07-01 00:00:00', 3])
+            ->andReturn('SELECT ...');
+
+        $this->db->shouldReceive('get_results')->andReturn([$this->row()]);
+
+        self::assertCount(1, $this->repo->findPaidBetween('2026-06-01 00:00:00', '2026-07-01 00:00:00', 3));
+    }
+
+    public function testFindPaidBetweenWithoutInstructorOmitsFilter(): void
+    {
+        $this->db->shouldReceive('prepare')
+            ->once()
+            ->with(Mockery::on(static fn (string $sql): bool => ! str_contains($sql, 'instructor_id')), ['paid', '2026-06-01 00:00:00', '2026-07-01 00:00:00'])
+            ->andReturn('SELECT ...');
+
+        $this->db->shouldReceive('get_results')->andReturn([]);
+
+        self::assertCount(0, $this->repo->findPaidBetween('2026-06-01 00:00:00', '2026-07-01 00:00:00'));
+    }
+
     public function testFindByRegistrationReturnsPayment(): void
     {
         $this->db->shouldReceive('prepare')
@@ -98,6 +134,8 @@ class PaymentRepositoryTest extends TestCase
             'currency'                 => 'CAD',
             'method'                   => Payment::METHOD_ETRANSFER,
             'status'                   => Payment::STATUS_PENDING,
+            'tax_rate'                 => '0.00',
+            'tax_amount'               => '0.00',
             'etransfer_email'          => null,
             'stripe_payment_intent_id' => null,
             'receipt_number'           => null,

tests/Unit/Payment/PaymentServiceTest.php

@@ -37,6 +37,7 @@ class PaymentServiceTest extends TestCase
         $this->enrollments = Mockery::mock(EnrollmentRepository::class);
         $this->settings    = Mockery::mock(StudioSettings::class);
         $this->settings->shouldReceive('etransferEmail')->andReturn('');
+        $this->settings->shouldReceive('hstRate')->andReturn(0.0)->byDefault();
 
         $this->service = new PaymentService(
             $this->payments,
@@ -91,6 +92,37 @@ class PaymentServiceTest extends TestCase
         );
     }
 
+    public function testHstIsComputedAndFrozenOntoPayment(): void
+    {
+        $this->settings->shouldReceive('hstRate')->andReturn(13.0);
+        $this->resolver->shouldReceive('resolve')->with(5)->andReturn(Payment::METHOD_ETRANSFER);
+        $this->payments->shouldReceive('insert')
+            ->once()
+            ->with(Mockery::on(static fn (Payment $p): bool => $p->taxRate === 13.0 && $p->taxAmount === 13.00 && $p->total() === 113.00))
+            ->andReturn(50);
+        $this->bookings->shouldReceive('setPaymentId')->once()->with(12, 50);
+        $this->payments->shouldReceive('findById')->with(50)->andReturn($this->payment(Payment::METHOD_ETRANSFER, Payment::STATUS_PENDING, 50));
+
+        self::assertNotNull($this->service->createForRegistration(Payment::REG_LESSON, 12, 5, 3, 100.00, 'CAD'));
+    }
+
+    public function testCompIsNotTaxed(): void
+    {
+        $this->settings->shouldReceive('hstRate')->andReturn(13.0);
+        $this->resolver->shouldReceive('resolve')->with(5)->andReturn(Payment::METHOD_COMP);
+        $this->payments->shouldReceive('insert')
+            ->once()
+            ->with(Mockery::on(static fn (Payment $p): bool => $p->taxRate === 0.0 && $p->taxAmount === 0.0))
+            ->andReturn(61);
+        $this->bookings->shouldReceive('setPaymentId')->once()->with(12, 61);
+        $this->payments->shouldReceive('markPaid')->once()->with(61, 'USC-61')->andReturn(true);
+        $this->bookings->shouldReceive('updateStatus')->once()->with(12, Lesson::STATUS_CONFIRMED)->andReturn(true);
+        $this->payments->shouldReceive('findById')->with(61)->andReturn($this->payment(Payment::METHOD_COMP, Payment::STATUS_PAID, 61));
+        $this->mailer->shouldReceive('send')->andReturn(false);
+
+        self::assertNotNull($this->service->createForRegistration(Payment::REG_LESSON, 12, 5, 3, 100.00, 'CAD'));
+    }
+
     public function testCompIsPaidAndConfirmsImmediately(): void
     {
         $this->resolver->shouldReceive('resolve')->with(5)->andReturn(Payment::METHOD_COMP);

tests/Unit/Payment/PaymentTest.php

@@ -39,6 +39,8 @@ class PaymentTest extends TestCase
             'currency'                 => 'CAD',
             'method'                   => Payment::METHOD_COMP,
             'status'                   => Payment::STATUS_PAID,
+            'tax_rate'                 => '13.00',
+            'tax_amount'               => '15.60',
             'etransfer_email'          => null,
             'stripe_payment_intent_id' => null,
             'receipt_number'           => 'USC-7',
@@ -48,16 +50,32 @@ class PaymentTest extends TestCase
 
         self::assertSame(7, $payment->id);
         self::assertSame(120.00, $payment->amount);
+        self::assertSame(13.00, $payment->taxRate);
+        self::assertSame(15.60, $payment->taxAmount);
         self::assertSame(Payment::METHOD_COMP, $payment->method);
         self::assertTrue($payment->isPaid());
         self::assertSame('USC-7', $payment->receiptNumber);
     }
 
+    public function testTotalAddsTaxToAmount(): void
+    {
+        $payment = new Payment(5, 3, Payment::REG_LESSON, 12, 100.00, taxRate: 13.0, taxAmount: 13.00);
+
+        self::assertSame(113.00, $payment->total());
+    }
+
+    public function testTotalEqualsAmountWhenUntaxed(): void
+    {
+        $payment = new Payment(5, 3, Payment::REG_LESSON, 12, 100.00);
+
+        self::assertSame(100.00, $payment->total());
+    }
+
     public function testToArrayContainsExpectedKeys(): void
     {
         $arr = (new Payment(5, 3, Payment::REG_LESSON, 12, 35.00, id: 7))->toArray();
 
-        foreach (['id', 'student_id', 'amount', 'currency', 'method', 'status', 'receipt_number'] as $key) {
+        foreach (['id', 'student_id', 'amount', 'tax_rate', 'tax_amount', 'total', 'currency', 'method', 'status', 'receipt_number'] as $key) {
             self::assertArrayHasKey($key, $arr);
         }
     }

tests/Unit/Payment/ReceiptMailerTest.php

@@ -32,4 +32,23 @@ class ReceiptMailerTest extends TestCase
 
         self::assertTrue((new ReceiptMailer())->send($payment, $student));
     }
+
+    public function testReceiptBreaksOutHstWhenTaxed(): void
+    {
+        Functions\expect('wp_mail')
+            ->once()
+            ->with(
+                'a@b.test',
+                Mockery::type('string'),
+                Mockery::on(static fn (string $body): bool => str_contains($body, 'HST') && str_contains($body, '113.00'))
+            )
+            ->andReturn(true);
+
+        $student             = Mockery::mock(\WP_User::class);
+        $student->user_email = 'a@b.test';
+
+        $payment = new Payment(5, 3, Payment::REG_LESSON, 12, 100.00, taxRate: 13.0, taxAmount: 13.00, receiptNumber: 'USC-1');
+
+        self::assertTrue((new ReceiptMailer())->send($payment, $student));
+    }
 }