diff --git a/tests/Feature/InvoiceServiceTest.php b/tests/Feature/InvoiceServiceTest.php
new file mode 100644
index 0000000..ce116d4
--- /dev/null
+++ b/tests/Feature/InvoiceServiceTest.php
@@ -0,0 +1,1161 @@
+<?php
+
+declare(strict_types=1);
+
+use Barryvdh\DomPDF\Facade\Pdf;
+use Core\Mod\Commerce\Mail\InvoiceGenerated;
+use Core\Mod\Commerce\Models\Invoice;
+use Core\Mod\Commerce\Models\InvoiceItem;
+use Core\Mod\Commerce\Models\Order;
+use Core\Mod\Commerce\Models\OrderItem;
+use Core\Mod\Commerce\Models\Payment;
+use Core\Mod\Commerce\Models\TaxRate;
+use Core\Mod\Commerce\Services\InvoiceService;
+use Core\Tenant\Models\User;
+use Core\Tenant\Models\Workspace;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Illuminate\Pagination\LengthAwarePaginator;
+use Illuminate\Support\Facades\Mail;
+use Illuminate\Support\Facades\Storage;
+
+uses(RefreshDatabase::class);
+
+beforeEach(function () {
+    Mail::fake();
+    Storage::fake('local');
+
+    $this->user = User::factory()->create();
+    $this->workspace = Workspace::factory()->create([
+        'billing_email' => 'billing@example.com',
+        'billing_name' => 'Test Company',
+        'billing_country' => 'GB',
+    ]);
+    $this->workspace->users()->attach($this->user->id, [
+        'role' => 'owner',
+        'is_default' => true,
+    ]);
+
+    // Seed UK VAT rate for tax calculations
+    TaxRate::create([
+        'country_code' => 'GB',
+        'name' => 'UK VAT',
+        'type' => 'vat',
+        'rate' => 20.00,
+        'is_digital_services' => true,
+        'effective_from' => '2020-01-01',
+        'is_active' => true,
+    ]);
+
+    $this->service = app(InvoiceService::class);
+});
+
+describe('InvoiceService', function () {
+    describe('createFromOrder()', function () {
+        it('creates an invoice from an order without payment', function () {
+            $order = Order::create([
+                'orderable_type' => Workspace::class,
+                'orderable_id' => $this->workspace->id,
+                'user_id' => $this->user->id,
+                'order_number' => 'ORD-20260324-ABC123',
+                'status' => 'pending',
+                'type' => 'subscription',
+                'currency' => 'GBP',
+                'subtotal' => 100.00,
+                'tax_amount' => 20.00,
+                'tax_rate' => 20.00,
+                'tax_country' => 'GB',
+                'discount_amount' => 0,
+                'total' => 120.00,
+                'billing_name' => 'Test Company',
+                'billing_email' => 'billing@example.com',
+            ]);
+
+            OrderItem::create([
+                'order_id' => $order->id,
+                'item_type' => 'package',
+                'description' => 'Creator Plan (Monthly)',
+                'quantity' => 1,
+                'unit_price' => 100.00,
+                'line_total' => 120.00,
+                'billing_cycle' => 'monthly',
+            ]);
+
+            $invoice = $this->service->createFromOrder($order);
+
+            expect($invoice)->toBeInstanceOf(Invoice::class)
+                ->and($invoice->workspace_id)->toBe($this->workspace->id)
+                ->and($invoice->order_id)->toBe($order->id)
+                ->and($invoice->payment_id)->toBeNull()
+                ->and($invoice->status)->toBe('pending')
+                ->and((float) $invoice->subtotal)->toBe(100.00)
+                ->and((float) $invoice->tax_amount)->toBe(20.00)
+                ->and((float) $invoice->total)->toBe(120.00)
+                ->and((float) $invoice->amount_paid)->toBe(0.00)
+                ->and((float) $invoice->amount_due)->toBe(120.00)
+                ->and($invoice->currency)->toBe('GBP')
+                ->and($invoice->billing_name)->toBe('Test Company')
+                ->and($invoice->billing_email)->toBe('billing@example.com')
+                ->and($invoice->invoice_number)->toStartWith('INV-');
+        });
+
+        it('creates a paid invoice when payment is provided', function () {
+            $order = Order::create([
+                'orderable_type' => Workspace::class,
+                'orderable_id' => $this->workspace->id,
+                'user_id' => $this->user->id,
+                'order_number' => 'ORD-20260324-DEF456',
+                'status' => 'paid',
+                'type' => 'subscription',
+                'currency' => 'GBP',
+                'subtotal' => 49.00,
+                'tax_amount' => 9.80,
+                'tax_rate' => 20.00,
+                'tax_country' => 'GB',
+                'discount_amount' => 0,
+                'total' => 58.80,
+                'billing_name' => 'Test Company',
+                'billing_email' => 'billing@example.com',
+            ]);
+
+            OrderItem::create([
+                'order_id' => $order->id,
+                'item_type' => 'package',
+                'description' => 'Agency Plan (Monthly)',
+                'quantity' => 1,
+                'unit_price' => 49.00,
+                'line_total' => 58.80,
+                'billing_cycle' => 'monthly',
+            ]);
+
+            $payment = Payment::create([
+                'workspace_id' => $this->workspace->id,
+                'gateway' => 'stripe',
+                'gateway_payment_id' => 'pi_test_paid',
+                'amount' => 58.80,
+                'fee' => 1.50,
+                'net_amount' => 57.30,
+                'refunded_amount' => 0,
+                'currency' => 'GBP',
+                'status' => 'succeeded',
+                'paid_at' => now(),
+            ]);
+
+            $invoice = $this->service->createFromOrder($order, $payment);
+
+            expect($invoice->status)->toBe('paid')
+                ->and($invoice->payment_id)->toBe($payment->id)
+                ->and((float) $invoice->amount_paid)->toBe(58.80)
+                ->and((float) $invoice->amount_due)->toBe(0.00)
+                ->and($invoice->paid_at)->not->toBeNull();
+        });
+
+        it('copies line items from the order to the invoice', function () {
+            $order = Order::create([
+                'orderable_type' => Workspace::class,
+                'orderable_id' => $this->workspace->id,
+                'user_id' => $this->user->id,
+                'order_number' => 'ORD-20260324-GHI789',
+                'status' => 'pending',
+                'type' => 'subscription',
+                'currency' => 'GBP',
+                'subtotal' => 68.00,
+                'tax_amount' => 13.60,
+                'tax_rate' => 20.00,
+                'tax_country' => 'GB',
+                'discount_amount' => 0,
+                'total' => 81.60,
+                'billing_name' => 'Test Company',
+                'billing_email' => 'billing@example.com',
+            ]);
+
+            $item1 = OrderItem::create([
+                'order_id' => $order->id,
+                'item_type' => 'package',
+                'description' => 'Agency Plan (Monthly)',
+                'quantity' => 1,
+                'unit_price' => 49.00,
+                'line_total' => 58.80,
+                'billing_cycle' => 'monthly',
+            ]);
+
+            $item2 = OrderItem::create([
+                'order_id' => $order->id,
+                'item_type' => 'addon',
+                'description' => 'Extra Storage',
+                'quantity' => 2,
+                'unit_price' => 9.50,
+                'line_total' => 22.80,
+                'billing_cycle' => 'monthly',
+            ]);
+
+            $invoice = $this->service->createFromOrder($order);
+
+            $invoiceItems = $invoice->items;
+            expect($invoiceItems)->toHaveCount(2);
+
+            $firstItem = $invoiceItems->where('order_item_id', $item1->id)->first();
+            expect($firstItem)->not->toBeNull()
+                ->and($firstItem->description)->toBe('Agency Plan (Monthly)')
+                ->and($firstItem->quantity)->toBe(1)
+                ->and((float) $firstItem->unit_price)->toBe(49.00)
+                ->and((float) $firstItem->line_total)->toBe(58.80);
+
+            $secondItem = $invoiceItems->where('order_item_id', $item2->id)->first();
+            expect($secondItem)->not->toBeNull()
+                ->and($secondItem->description)->toBe('Extra Storage')
+                ->and($secondItem->quantity)->toBe(2)
+                ->and((float) $secondItem->unit_price)->toBe(9.50)
+                ->and((float) $secondItem->line_total)->toBe(22.80);
+        });
+
+        it('generates sequential invoice numbers within a year', function () {
+            $order = Order::create([
+                'orderable_type' => Workspace::class,
+                'orderable_id' => $this->workspace->id,
+                'user_id' => $this->user->id,
+                'order_number' => 'ORD-20260324-SEQ001',
+                'status' => 'pending',
+                'type' => 'subscription',
+                'currency' => 'GBP',
+                'subtotal' => 19.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 19.00,
+                'billing_name' => 'Test Company',
+                'billing_email' => 'billing@example.com',
+            ]);
+
+            // Ensure at least one order item exists for the relationship
+            OrderItem::create([
+                'order_id' => $order->id,
+                'item_type' => 'package',
+                'description' => 'Plan',
+                'quantity' => 1,
+                'unit_price' => 19.00,
+                'line_total' => 19.00,
+                'billing_cycle' => 'monthly',
+            ]);
+
+            $invoice1 = $this->service->createFromOrder($order);
+
+            $order2 = Order::create([
+                'orderable_type' => Workspace::class,
+                'orderable_id' => $this->workspace->id,
+                'user_id' => $this->user->id,
+                'order_number' => 'ORD-20260324-SEQ002',
+                'status' => 'pending',
+                'type' => 'subscription',
+                'currency' => 'GBP',
+                'subtotal' => 29.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 29.00,
+                'billing_name' => 'Test Company',
+                'billing_email' => 'billing@example.com',
+            ]);
+
+            OrderItem::create([
+                'order_id' => $order2->id,
+                'item_type' => 'package',
+                'description' => 'Plan 2',
+                'quantity' => 1,
+                'unit_price' => 29.00,
+                'line_total' => 29.00,
+                'billing_cycle' => 'monthly',
+            ]);
+
+            $invoice2 = $this->service->createFromOrder($order2);
+
+            // Both should have valid prefixed invoice numbers
+            $year = now()->format('Y');
+            expect($invoice1->invoice_number)->toMatch("/^INV-{$year}-\\d{4}$/")
+                ->and($invoice2->invoice_number)->toMatch("/^INV-{$year}-\\d{4}$/");
+
+            // Second invoice number should be greater than first
+            $num1 = (int) substr($invoice1->invoice_number, -4);
+            $num2 = (int) substr($invoice2->invoice_number, -4);
+            expect($num2)->toBe($num1 + 1);
+        });
+
+        it('sets correct due date from config', function () {
+            config(['commerce.billing.invoice_due_days' => 30]);
+
+            $order = Order::create([
+                'orderable_type' => Workspace::class,
+                'orderable_id' => $this->workspace->id,
+                'user_id' => $this->user->id,
+                'order_number' => 'ORD-20260324-DUE001',
+                'status' => 'pending',
+                'type' => 'subscription',
+                'currency' => 'GBP',
+                'subtotal' => 19.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 19.00,
+                'billing_name' => 'Test Company',
+                'billing_email' => 'billing@example.com',
+            ]);
+
+            OrderItem::create([
+                'order_id' => $order->id,
+                'item_type' => 'package',
+                'description' => 'Plan',
+                'quantity' => 1,
+                'unit_price' => 19.00,
+                'line_total' => 19.00,
+                'billing_cycle' => 'monthly',
+            ]);
+
+            $invoice = $this->service->createFromOrder($order);
+
+            expect($invoice->issue_date->toDateString())->toBe(now()->toDateString())
+                ->and($invoice->due_date->toDateString())->toBe(now()->addDays(30)->toDateString());
+        });
+    });
+
+    describe('createForRenewal()', function () {
+        it('creates a pending invoice for subscription renewal', function () {
+            $invoice = $this->service->createForRenewal(
+                $this->workspace,
+                19.00,
+                'Creator Plan - Monthly Renewal'
+            );
+
+            expect($invoice)->toBeInstanceOf(Invoice::class)
+                ->and($invoice->workspace_id)->toBe($this->workspace->id)
+                ->and($invoice->status)->toBe('pending')
+                ->and((float) $invoice->subtotal)->toBe(19.00)
+                ->and((float) $invoice->amount_due)->toBeGreaterThan(0.0)
+                ->and((float) $invoice->amount_paid)->toBe(0.00)
+                ->and($invoice->billing_name)->toBe('Test Company')
+                ->and($invoice->billing_email)->toBe('billing@example.com');
+        });
+
+        it('creates a paid renewal invoice when payment is provided', function () {
+            $payment = Payment::create([
+                'workspace_id' => $this->workspace->id,
+                'gateway' => 'btcpay',
+                'gateway_payment_id' => 'btc_renewal_001',
+                'amount' => 22.80,
+                'fee' => 0,
+                'net_amount' => 22.80,
+                'refunded_amount' => 0,
+                'currency' => 'GBP',
+                'status' => 'succeeded',
+                'paid_at' => now(),
+            ]);
+
+            $invoice = $this->service->createForRenewal(
+                $this->workspace,
+                19.00,
+                'Creator Plan - Monthly Renewal',
+                $payment
+            );
+
+            expect($invoice->status)->toBe('paid')
+                ->and($invoice->payment_id)->toBe($payment->id)
+                ->and((float) $invoice->amount_due)->toBe(0.00)
+                ->and($invoice->paid_at)->not->toBeNull();
+        });
+
+        it('calculates tax correctly for UK workspace', function () {
+            $invoice = $this->service->createForRenewal(
+                $this->workspace,
+                100.00,
+                'Agency Plan - Monthly Renewal'
+            );
+
+            // UK VAT at 20%
+            expect((float) $invoice->subtotal)->toBe(100.00)
+                ->and((float) $invoice->tax_amount)->toBe(20.00)
+                ->and((float) $invoice->tax_rate)->toBe(20.00)
+                ->and((float) $invoice->total)->toBe(120.00)
+                ->and($invoice->tax_country)->toBe('GB');
+        });
+
+        it('creates a single line item for the renewal', function () {
+            $invoice = $this->service->createForRenewal(
+                $this->workspace,
+                49.00,
+                'Agency Plan - Monthly Renewal'
+            );
+
+            $items = $invoice->items;
+            expect($items)->toHaveCount(1);
+
+            $item = $items->first();
+            expect($item->description)->toBe('Agency Plan - Monthly Renewal')
+                ->and($item->quantity)->toBe(1)
+                ->and((float) $item->unit_price)->toBe(49.00)
+                ->and((float) $item->tax_rate)->toBe(20.00)
+                ->and((float) $item->tax_amount)->toBe(9.80);
+        });
+
+        it('uses the configured default currency', function () {
+            config(['commerce.currency' => 'USD']);
+
+            $invoice = $this->service->createForRenewal(
+                $this->workspace,
+                19.00,
+                'Creator Plan - Monthly Renewal'
+            );
+
+            expect($invoice->currency)->toBe('USD');
+        });
+    });
+
+    describe('markAsPaid()', function () {
+        it('transitions invoice from pending to paid', function () {
+            $invoice = Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-1001',
+                'status' => 'pending',
+                'subtotal' => 19.00,
+                'tax_amount' => 3.80,
+                'discount_amount' => 0,
+                'total' => 22.80,
+                'amount_paid' => 0,
+                'amount_due' => 22.80,
+                'currency' => 'GBP',
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+            ]);
+
+            $payment = Payment::create([
+                'workspace_id' => $this->workspace->id,
+                'gateway' => 'stripe',
+                'gateway_payment_id' => 'pi_mark_paid',
+                'amount' => 22.80,
+                'fee' => 0.50,
+                'net_amount' => 22.30,
+                'refunded_amount' => 0,
+                'currency' => 'GBP',
+                'status' => 'succeeded',
+                'paid_at' => now(),
+            ]);
+
+            $this->service->markAsPaid($invoice, $payment);
+
+            $invoice->refresh();
+            expect($invoice->status)->toBe('paid')
+                ->and($invoice->payment_id)->toBe($payment->id)
+                ->and((float) $invoice->amount_paid)->toBe(22.80)
+                ->and((float) $invoice->amount_due)->toBe(0.00)
+                ->and($invoice->paid_at)->not->toBeNull();
+        });
+    });
+
+    describe('void()', function () {
+        it('transitions invoice to void status', function () {
+            $invoice = Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-2001',
+                'status' => 'pending',
+                'subtotal' => 19.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 19.00,
+                'amount_paid' => 0,
+                'amount_due' => 19.00,
+                'currency' => 'GBP',
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+            ]);
+
+            $this->service->void($invoice);
+
+            $invoice->refresh();
+            expect($invoice->status)->toBe('void')
+                ->and($invoice->isVoid())->toBeTrue();
+        });
+    });
+
+    describe('generatePdf()', function () {
+        it('generates a PDF and stores it on disk', function () {
+            $invoice = Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-3001',
+                'status' => 'paid',
+                'subtotal' => 49.00,
+                'tax_amount' => 9.80,
+                'discount_amount' => 0,
+                'total' => 58.80,
+                'amount_paid' => 58.80,
+                'amount_due' => 0,
+                'currency' => 'GBP',
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+                'paid_at' => now(),
+            ]);
+
+            InvoiceItem::create([
+                'invoice_id' => $invoice->id,
+                'description' => 'Agency Plan (Monthly)',
+                'quantity' => 1,
+                'unit_price' => 49.00,
+                'line_total' => 58.80,
+                'tax_rate' => 20.00,
+                'tax_amount' => 9.80,
+            ]);
+
+            // Mock the PDF facade
+            $mockPdf = Mockery::mock();
+            $mockPdf->shouldReceive('output')->andReturn('%PDF-1.4 fake content');
+            Pdf::shouldReceive('loadView')
+                ->once()
+                ->with('commerce::pdf.invoice', Mockery::type('array'))
+                ->andReturn($mockPdf);
+
+            $filename = $this->service->generatePdf($invoice);
+
+            expect($filename)->toContain($invoice->invoice_number)
+                ->and($filename)->toContain((string) $this->workspace->id);
+
+            Storage::disk('local')->assertExists($filename);
+
+            $invoice->refresh();
+            expect($invoice->pdf_path)->toBe($filename);
+        });
+
+        it('stores PDF in configured storage path', function () {
+            config(['commerce.pdf.storage_path' => 'custom-invoices']);
+
+            $invoice = Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-3002',
+                'status' => 'paid',
+                'subtotal' => 19.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 19.00,
+                'amount_paid' => 19.00,
+                'amount_due' => 0,
+                'currency' => 'GBP',
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+                'paid_at' => now(),
+            ]);
+
+            $mockPdf = Mockery::mock();
+            $mockPdf->shouldReceive('output')->andReturn('%PDF-1.4 fake content');
+            Pdf::shouldReceive('loadView')->andReturn($mockPdf);
+
+            $filename = $this->service->generatePdf($invoice);
+
+            expect($filename)->toStartWith('custom-invoices/');
+        });
+    });
+
+    describe('getPdf()', function () {
+        it('returns existing PDF path when file exists on disk', function () {
+            $invoice = Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-4001',
+                'status' => 'paid',
+                'subtotal' => 19.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 19.00,
+                'amount_paid' => 19.00,
+                'amount_due' => 0,
+                'currency' => 'GBP',
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+                'pdf_path' => "invoices/{$this->workspace->id}/INV-2026-4001.pdf",
+            ]);
+
+            // Put a file on the faked disk
+            Storage::disk('local')->put($invoice->pdf_path, 'existing pdf content');
+
+            $path = $this->service->getPdf($invoice);
+
+            expect($path)->toBe($invoice->pdf_path);
+        });
+
+        it('generates a new PDF when file does not exist', function () {
+            $invoice = Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-4002',
+                'status' => 'paid',
+                'subtotal' => 19.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 19.00,
+                'amount_paid' => 19.00,
+                'amount_due' => 0,
+                'currency' => 'GBP',
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+                'pdf_path' => null,
+            ]);
+
+            $mockPdf = Mockery::mock();
+            $mockPdf->shouldReceive('output')->andReturn('%PDF-1.4 fake content');
+            Pdf::shouldReceive('loadView')->andReturn($mockPdf);
+
+            $path = $this->service->getPdf($invoice);
+
+            expect($path)->toContain($invoice->invoice_number);
+            Storage::disk('local')->assertExists($path);
+        });
+    });
+
+    describe('sendEmail()', function () {
+        it('queues an invoice email to the billing address', function () {
+            $invoice = Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-5001',
+                'status' => 'paid',
+                'subtotal' => 19.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 19.00,
+                'amount_paid' => 19.00,
+                'amount_due' => 0,
+                'currency' => 'GBP',
+                'billing_email' => 'invoices@example.com',
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+                'pdf_path' => "invoices/{$this->workspace->id}/INV-2026-5001.pdf",
+            ]);
+
+            // Ensure the PDF exists so getPdf returns immediately
+            Storage::disk('local')->put($invoice->pdf_path, 'pdf content');
+
+            $this->service->sendEmail($invoice);
+
+            Mail::assertQueued(InvoiceGenerated::class, function ($mailable) {
+                return $mailable->hasTo('invoices@example.com');
+            });
+        });
+
+        it('does not send email when config is disabled', function () {
+            config(['commerce.billing.send_invoice_emails' => false]);
+
+            $invoice = Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-5002',
+                'status' => 'paid',
+                'subtotal' => 19.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 19.00,
+                'amount_paid' => 19.00,
+                'amount_due' => 0,
+                'currency' => 'GBP',
+                'billing_email' => 'invoices@example.com',
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+            ]);
+
+            $this->service->sendEmail($invoice);
+
+            Mail::assertNothingQueued();
+        });
+
+        it('does not send email when no recipient can be resolved', function () {
+            $invoice = Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-5003',
+                'status' => 'paid',
+                'subtotal' => 19.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 19.00,
+                'amount_paid' => 19.00,
+                'amount_due' => 0,
+                'currency' => 'GBP',
+                'billing_email' => null,
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+                'pdf_path' => "invoices/{$this->workspace->id}/INV-2026-5003.pdf",
+            ]);
+
+            // Clear workspace billing email so fallback also fails
+            $this->workspace->update(['billing_email' => null]);
+
+            Storage::disk('local')->put($invoice->pdf_path, 'pdf content');
+
+            $this->service->sendEmail($invoice);
+
+            Mail::assertNothingQueued();
+        });
+    });
+
+    describe('getForWorkspace()', function () {
+        it('returns paginated invoices for a workspace', function () {
+            // Create several invoices
+            foreach (range(1, 5) as $i) {
+                Invoice::create([
+                    'workspace_id' => $this->workspace->id,
+                    'invoice_number' => "INV-2026-600{$i}",
+                    'status' => $i <= 3 ? 'paid' : 'pending',
+                    'subtotal' => 19.00,
+                    'tax_amount' => 0,
+                    'discount_amount' => 0,
+                    'total' => 19.00,
+                    'amount_paid' => $i <= 3 ? 19.00 : 0,
+                    'amount_due' => $i <= 3 ? 0 : 19.00,
+                    'currency' => 'GBP',
+                    'issue_date' => now(),
+                    'due_date' => now()->addDays(14),
+                ]);
+            }
+
+            $result = $this->service->getForWorkspace($this->workspace, 3);
+
+            expect($result)->toBeInstanceOf(LengthAwarePaginator::class)
+                ->and($result->total())->toBe(5)
+                ->and($result->perPage())->toBe(3)
+                ->and($result->count())->toBe(3);
+        });
+
+        it('does not return invoices from other workspaces', function () {
+            $otherWorkspace = Workspace::factory()->create();
+
+            Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-6010',
+                'status' => 'paid',
+                'subtotal' => 19.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 19.00,
+                'amount_paid' => 19.00,
+                'amount_due' => 0,
+                'currency' => 'GBP',
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+            ]);
+
+            Invoice::create([
+                'workspace_id' => $otherWorkspace->id,
+                'invoice_number' => 'INV-2026-6011',
+                'status' => 'paid',
+                'subtotal' => 29.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 29.00,
+                'amount_paid' => 29.00,
+                'amount_due' => 0,
+                'currency' => 'GBP',
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+            ]);
+
+            $result = $this->service->getForWorkspace($this->workspace);
+
+            expect($result->total())->toBe(1);
+        });
+    });
+
+    describe('getUnpaidForWorkspace()', function () {
+        it('returns pending invoices that are not yet due', function () {
+            // Pending, not yet due
+            Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-7001',
+                'status' => 'pending',
+                'subtotal' => 19.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 19.00,
+                'amount_paid' => 0,
+                'amount_due' => 19.00,
+                'currency' => 'GBP',
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+            ]);
+
+            // Paid invoice (should not appear)
+            Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-7002',
+                'status' => 'paid',
+                'subtotal' => 29.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 29.00,
+                'amount_paid' => 29.00,
+                'amount_due' => 0,
+                'currency' => 'GBP',
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+            ]);
+
+            // Overdue invoice (due_date in the past, should not appear)
+            Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-7003',
+                'status' => 'pending',
+                'subtotal' => 39.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 39.00,
+                'amount_paid' => 0,
+                'amount_due' => 39.00,
+                'currency' => 'GBP',
+                'issue_date' => now()->subDays(30),
+                'due_date' => now()->subDays(7),
+            ]);
+
+            $unpaid = $this->service->getUnpaidForWorkspace($this->workspace);
+
+            expect($unpaid)->toHaveCount(1)
+                ->and($unpaid->first()->invoice_number)->toBe('INV-2026-7001');
+        });
+    });
+
+    describe('getOverdueForWorkspace()', function () {
+        it('returns pending invoices that are past due', function () {
+            // Overdue pending
+            Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-8001',
+                'status' => 'pending',
+                'subtotal' => 19.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 19.00,
+                'amount_paid' => 0,
+                'amount_due' => 19.00,
+                'currency' => 'GBP',
+                'issue_date' => now()->subDays(30),
+                'due_date' => now()->subDays(7),
+            ]);
+
+            // Not yet due (should not appear)
+            Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-8002',
+                'status' => 'pending',
+                'subtotal' => 29.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 29.00,
+                'amount_paid' => 0,
+                'amount_due' => 29.00,
+                'currency' => 'GBP',
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+            ]);
+
+            // Paid (should not appear)
+            Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-8003',
+                'status' => 'paid',
+                'subtotal' => 39.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 39.00,
+                'amount_paid' => 39.00,
+                'amount_due' => 0,
+                'currency' => 'GBP',
+                'issue_date' => now()->subDays(30),
+                'due_date' => now()->subDays(7),
+            ]);
+
+            $overdue = $this->service->getOverdueForWorkspace($this->workspace);
+
+            expect($overdue)->toHaveCount(1)
+                ->and($overdue->first()->invoice_number)->toBe('INV-2026-8001');
+        });
+    });
+});
+
+describe('Invoice model', function () {
+    beforeEach(function () {
+        $this->invoice = Invoice::create([
+            'workspace_id' => $this->workspace->id,
+            'invoice_number' => 'INV-2026-9001',
+            'status' => 'pending',
+            'subtotal' => 100.00,
+            'tax_amount' => 20.00,
+            'discount_amount' => 0,
+            'total' => 120.00,
+            'amount_paid' => 0,
+            'amount_due' => 120.00,
+            'currency' => 'GBP',
+            'issue_date' => now(),
+            'due_date' => now()->addDays(14),
+        ]);
+    });
+
+    describe('status helpers', function () {
+        it('identifies pending invoices', function () {
+            expect($this->invoice->isPending())->toBeTrue()
+                ->and($this->invoice->isPaid())->toBeFalse()
+                ->and($this->invoice->isVoid())->toBeFalse();
+        });
+
+        it('identifies paid invoices', function () {
+            $this->invoice->update(['status' => 'paid']);
+
+            expect($this->invoice->isPaid())->toBeTrue()
+                ->and($this->invoice->isPending())->toBeFalse();
+        });
+
+        it('identifies void invoices', function () {
+            $this->invoice->update(['status' => 'void']);
+
+            expect($this->invoice->isVoid())->toBeTrue()
+                ->and($this->invoice->isPending())->toBeFalse();
+        });
+
+        it('identifies overdue invoices by status', function () {
+            $this->invoice->update(['status' => 'overdue']);
+
+            expect($this->invoice->isOverdue())->toBeTrue();
+        });
+
+        it('identifies overdue invoices by past due date', function () {
+            $this->invoice->update(['due_date' => now()->subDays(1)]);
+
+            expect($this->invoice->isOverdue())->toBeTrue();
+        });
+
+        it('identifies sent invoices', function () {
+            $this->invoice->update(['status' => 'sent']);
+
+            expect($this->invoice->isSent())->toBeTrue()
+                ->and($this->invoice->isPending())->toBeTrue(); // sent is considered pending
+        });
+
+        it('identifies draft invoices', function () {
+            $this->invoice->update(['status' => 'draft']);
+
+            expect($this->invoice->isDraft())->toBeTrue()
+                ->and($this->invoice->isPending())->toBeTrue(); // draft is considered pending
+        });
+    });
+
+    describe('actions', function () {
+        it('marks invoice as paid with payment', function () {
+            $payment = Payment::create([
+                'workspace_id' => $this->workspace->id,
+                'gateway' => 'stripe',
+                'gateway_payment_id' => 'pi_model_test',
+                'amount' => 120.00,
+                'fee' => 3.00,
+                'net_amount' => 117.00,
+                'refunded_amount' => 0,
+                'currency' => 'GBP',
+                'status' => 'succeeded',
+                'paid_at' => now(),
+            ]);
+
+            $this->invoice->markAsPaid($payment);
+
+            expect($this->invoice->status)->toBe('paid')
+                ->and($this->invoice->payment_id)->toBe($payment->id)
+                ->and((float) $this->invoice->amount_paid)->toBe(120.00)
+                ->and((float) $this->invoice->amount_due)->toBe(0.00)
+                ->and($this->invoice->paid_at)->not->toBeNull();
+        });
+
+        it('marks invoice as void', function () {
+            $this->invoice->markAsVoid();
+
+            expect($this->invoice->status)->toBe('void');
+        });
+
+        it('marks invoice as sent', function () {
+            $this->invoice->send();
+
+            expect($this->invoice->status)->toBe('sent');
+        });
+    });
+
+    describe('scopes', function () {
+        it('scopes to paid invoices', function () {
+            $this->invoice->update(['status' => 'paid']);
+
+            Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-9002',
+                'status' => 'pending',
+                'subtotal' => 50.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 50.00,
+                'amount_paid' => 0,
+                'amount_due' => 50.00,
+                'currency' => 'GBP',
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+            ]);
+
+            $paid = Invoice::paid()->get();
+
+            expect($paid)->toHaveCount(1)
+                ->and($paid->first()->id)->toBe($this->invoice->id);
+        });
+
+        it('scopes to unpaid invoices', function () {
+            Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => 'INV-2026-9003',
+                'status' => 'paid',
+                'subtotal' => 50.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 50.00,
+                'amount_paid' => 50.00,
+                'amount_due' => 0,
+                'currency' => 'GBP',
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+            ]);
+
+            $unpaid = Invoice::unpaid()->get();
+
+            expect($unpaid)->toHaveCount(1)
+                ->and($unpaid->first()->id)->toBe($this->invoice->id);
+        });
+
+        it('scopes to workspace invoices', function () {
+            $otherWorkspace = Workspace::factory()->create();
+
+            Invoice::create([
+                'workspace_id' => $otherWorkspace->id,
+                'invoice_number' => 'INV-2026-9004',
+                'status' => 'pending',
+                'subtotal' => 50.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 50.00,
+                'amount_paid' => 0,
+                'amount_due' => 50.00,
+                'currency' => 'GBP',
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+            ]);
+
+            $workspaceInvoices = Invoice::forWorkspace($this->workspace->id)->get();
+
+            expect($workspaceInvoices)->toHaveCount(1)
+                ->and($workspaceInvoices->first()->id)->toBe($this->invoice->id);
+        });
+    });
+
+    describe('invoice number generation', function () {
+        it('generates invoice numbers with correct format', function () {
+            $number = Invoice::generateInvoiceNumber();
+            $year = now()->format('Y');
+
+            expect($number)->toMatch("/^INV-{$year}-\\d{4}$/");
+        });
+
+        it('increments invoice numbers sequentially', function () {
+            $number1 = Invoice::generateInvoiceNumber();
+
+            Invoice::create([
+                'workspace_id' => $this->workspace->id,
+                'invoice_number' => $number1,
+                'status' => 'pending',
+                'subtotal' => 10.00,
+                'tax_amount' => 0,
+                'discount_amount' => 0,
+                'total' => 10.00,
+                'amount_paid' => 0,
+                'amount_due' => 10.00,
+                'currency' => 'GBP',
+                'issue_date' => now(),
+                'due_date' => now()->addDays(14),
+            ]);
+
+            $number2 = Invoice::generateInvoiceNumber();
+
+            $seq1 = (int) substr($number1, -4);
+            $seq2 = (int) substr($number2, -4);
+
+            expect($seq2)->toBe($seq1 + 1);
+        });
+    });
+
+    describe('relationships', function () {
+        it('belongs to a workspace', function () {
+            expect($this->invoice->workspace)->toBeInstanceOf(Workspace::class)
+                ->and($this->invoice->workspace->id)->toBe($this->workspace->id);
+        });
+
+        it('has many items', function () {
+            InvoiceItem::create([
+                'invoice_id' => $this->invoice->id,
+                'description' => 'Line item 1',
+                'quantity' => 1,
+                'unit_price' => 60.00,
+                'line_total' => 72.00,
+                'tax_rate' => 20.00,
+                'tax_amount' => 12.00,
+            ]);
+
+            InvoiceItem::create([
+                'invoice_id' => $this->invoice->id,
+                'description' => 'Line item 2',
+                'quantity' => 2,
+                'unit_price' => 20.00,
+                'line_total' => 48.00,
+                'tax_rate' => 20.00,
+                'tax_amount' => 8.00,
+            ]);
+
+            expect($this->invoice->items)->toHaveCount(2);
+        });
+
+        it('belongs to an order', function () {
+            $order = Order::create([
+                'orderable_type' => Workspace::class,
+                'orderable_id' => $this->workspace->id,
+                'user_id' => $this->user->id,
+                'order_number' => 'ORD-20260324-REL001',
+                'status' => 'paid',
+                'type' => 'subscription',
+                'currency' => 'GBP',
+                'subtotal' => 100.00,
+                'tax_amount' => 20.00,
+                'discount_amount' => 0,
+                'total' => 120.00,
+            ]);
+
+            $this->invoice->update(['order_id' => $order->id]);
+            $this->invoice->refresh();
+
+            expect($this->invoice->order)->toBeInstanceOf(Order::class)
+                ->and($this->invoice->order->id)->toBe($order->id);
+        });
+
+        it('belongs to a payment', function () {
+            $payment = Payment::create([
+                'workspace_id' => $this->workspace->id,
+                'gateway' => 'stripe',
+                'gateway_payment_id' => 'pi_rel_test',
+                'amount' => 120.00,
+                'fee' => 0,
+                'net_amount' => 120.00,
+                'refunded_amount' => 0,
+                'currency' => 'GBP',
+                'status' => 'succeeded',
+            ]);
+
+            $this->invoice->update(['payment_id' => $payment->id]);
+            $this->invoice->refresh();
+
+            expect($this->invoice->payment)->toBeInstanceOf(Payment::class)
+                ->and($this->invoice->payment->id)->toBe($payment->id);
+        });
+    });
+
+    describe('issued_at accessor', function () {
+        it('returns issue_date as issued_at alias', function () {
+            expect($this->invoice->issued_at)->not->toBeNull()
+                ->and($this->invoice->issued_at->toDateString())
+                ->toBe($this->invoice->issue_date->toDateString());
+        });
+    });
+});
+
+afterEach(function () {
+    Mockery::close();
+});