Added tax support

app/Domains/Admin/Actions/UpdateTenantTax/UpdateTenantTaxAction.php

@@ -0,0 +1,64 @@
+<?php
+
+namespace App\Domains\Admin\Actions\UpdateTenantTax;
+
+use App\Enumerations\TaxExemptionReason;
+
+class UpdateTenantTaxAction
+{
+    public function __construct(private UpdateTenantTaxRequest $request)
+    {
+    }
+
+    public function execute(): UpdateTenantTaxResponse
+    {
+        $response = new UpdateTenantTaxResponse();
+
+        if ($this->request->taxLiable) {
+            $this->request->tenant->update([
+                'tax_liable' => true,
+                'vat_rate' => $this->clampVatRate($this->request->vatRate),
+                'tax_exemption_reason' => null,
+                'tax_exemption_note' => null,
+            ]);
+
+            $response->success = true;
+            $response->message = 'Steuerinformationen wurden gespeichert.';
+
+            return $response;
+        }
+
+        $reason = TaxExemptionReason::tryFrom((string)$this->request->exemptionReason);
+
+        if ($reason === null) {
+            $response->message = 'Bitte einen gültigen Befreiungsgrund auswählen.';
+
+            return $response;
+        }
+
+        $note = trim((string)$this->request->exemptionNote);
+
+        if ($reason->requiresNote() && $note === '') {
+            $response->message = 'Bitte einen Text für den Befreiungsgrund angeben.';
+
+            return $response;
+        }
+
+        $this->request->tenant->update([
+            'tax_liable' => false,
+            'vat_rate' => 0,
+            'tax_exemption_reason' => $reason->value,
+            'tax_exemption_note' => $reason->requiresNote() ? $note : null,
+        ]);
+
+        $response->success = true;
+        $response->message = 'Steuerinformationen wurden gespeichert.';
+
+        return $response;
+    }
+
+    private function clampVatRate(int $vatRate): int
+    {
+        return max(0, min(100, $vatRate));
+    }
+}

app/Domains/Admin/Actions/UpdateTenantTax/UpdateTenantTaxRequest.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace App\Domains\Admin\Actions\UpdateTenantTax;
+
+use App\Models\Tenant;
+
+class UpdateTenantTaxRequest
+{
+    public function __construct(
+        public Tenant  $tenant,
+        public bool    $taxLiable,
+        public int     $vatRate,
+        public ?string $exemptionReason,
+        public ?string $exemptionNote,
+    )
+    {
+    }
+}

app/Domains/Admin/Actions/UpdateTenantTax/UpdateTenantTaxResponse.php

@@ -0,0 +1,9 @@
+<?php
+
+namespace App\Domains\Admin\Actions\UpdateTenantTax;
+
+class UpdateTenantTaxResponse
+{
+    public bool $success = false;
+    public string $message = '';
+}

app/Domains/Admin/Controllers/ManagedTenantTaxGetController.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace App\Domains\Admin\Controllers;
+
+use App\Enumerations\TaxExemptionReason;
+use App\Scopes\CommonController;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Request;
+
+class ManagedTenantTaxGetController extends CommonController
+{
+    public function __invoke(string $slug, Request $request): JsonResponse
+    {
+        $tenant = $this->adminTenants->findBySlug($slug);
+
+        return response()->json([
+            'tax_liable' => $tenant->tax_liable,
+            'vat_rate' => $tenant->vat_rate,
+            'tax_exemption_reason' => $tenant->tax_exemption_reason,
+            'tax_exemption_note' => $tenant->tax_exemption_note,
+            'exemption_reasons' => TaxExemptionReason::options(),
+            'saveEndpoint' => '/api/v1/admin/tenants/' . $slug . '/tax',
+        ]);
+    }
+}

app/Domains/Admin/Controllers/ManagedTenantTaxUpdateController.php

@@ -0,0 +1,32 @@
+<?php
+
+namespace App\Domains\Admin\Controllers;
+
+use App\Domains\Admin\Actions\UpdateTenantTax\UpdateTenantTaxAction;
+use App\Domains\Admin\Actions\UpdateTenantTax\UpdateTenantTaxRequest;
+use App\Scopes\CommonController;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Request;
+
+class ManagedTenantTaxUpdateController extends CommonController
+{
+    public function __invoke(string $slug, Request $request): JsonResponse
+    {
+        $tenant = $this->adminTenants->findBySlug($slug);
+
+        $action = new UpdateTenantTaxAction(new UpdateTenantTaxRequest(
+            tenant: $tenant,
+            taxLiable: $request->boolean('tax_liable'),
+            vatRate: (int)$request->input('vat_rate', 0),
+            exemptionReason: $request->input('tax_exemption_reason'),
+            exemptionNote: $request->input('tax_exemption_note'),
+        ));
+
+        $response = $action->execute();
+
+        return response()->json([
+            'status' => $response->success ? 'success' : 'error',
+            'message' => $response->message,
+        ]);
+    }
+}

app/Domains/Admin/Controllers/TenantTaxGetController.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace App\Domains\Admin\Controllers;
+
+use App\Enumerations\TaxExemptionReason;
+use App\Scopes\CommonController;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Request;
+
+class TenantTaxGetController extends CommonController
+{
+    public function __invoke(Request $request): JsonResponse
+    {
+        return response()->json([
+            'tax_liable' => $this->tenant->tax_liable,
+            'vat_rate' => $this->tenant->vat_rate,
+            'tax_exemption_reason' => $this->tenant->tax_exemption_reason,
+            'tax_exemption_note' => $this->tenant->tax_exemption_note,
+            'exemption_reasons' => TaxExemptionReason::options(),
+            'saveEndpoint' => '/api/v1/admin/tenant/tax',
+        ]);
+    }
+}

app/Domains/Admin/Controllers/TenantTaxUpdateController.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace App\Domains\Admin\Controllers;
+
+use App\Domains\Admin\Actions\UpdateTenantTax\UpdateTenantTaxAction;
+use App\Domains\Admin\Actions\UpdateTenantTax\UpdateTenantTaxRequest;
+use App\Scopes\CommonController;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Request;
+
+class TenantTaxUpdateController extends CommonController
+{
+    public function __invoke(Request $request): JsonResponse
+    {
+        $action = new UpdateTenantTaxAction(new UpdateTenantTaxRequest(
+            tenant: $this->tenant,
+            taxLiable: $request->boolean('tax_liable'),
+            vatRate: (int)$request->input('vat_rate', 0),
+            exemptionReason: $request->input('tax_exemption_reason'),
+            exemptionNote: $request->input('tax_exemption_note'),
+        ));
+
+        $response = $action->execute();
+
+        return response()->json([
+            'status' => $response->success ? 'success' : 'error',
+            'message' => $response->message,
+        ]);
+    }
+}

app/Domains/Admin/Routes/api.php

@@ -1,10 +1,5 @@
 <?php
 
-use App\Domains\Admin\Controllers\UserDetailGetController;
-use App\Domains\Admin\Controllers\UserListApiController;
-use App\Domains\Admin\Controllers\UserResetPasswordController;
-use App\Domains\Admin\Controllers\UserToggleActiveController;
-use App\Domains\Admin\Controllers\UserUpdateController;
 use App\Domains\Admin\Controllers\ManagedTenantContactGetController;
 use App\Domains\Admin\Controllers\ManagedTenantContactUpdateController;
 use App\Domains\Admin\Controllers\ManagedTenantGdprGetController;
@@ -13,6 +8,8 @@ use App\Domains\Admin\Controllers\ManagedTenantImpressGetController;
 use App\Domains\Admin\Controllers\ManagedTenantImpressUpdateController;
 use App\Domains\Admin\Controllers\ManagedTenantPaymentGetController;
 use App\Domains\Admin\Controllers\ManagedTenantPaymentUpdateController;
+use App\Domains\Admin\Controllers\ManagedTenantTaxGetController;
+use App\Domains\Admin\Controllers\ManagedTenantTaxUpdateController;
 use App\Domains\Admin\Controllers\TenantContactGetController;
 use App\Domains\Admin\Controllers\TenantContactUpdateController;
 use App\Domains\Admin\Controllers\TenantCreateController;
@@ -24,9 +21,16 @@ use App\Domains\Admin\Controllers\TenantImpressGetController;
 use App\Domains\Admin\Controllers\TenantImpressUpdateController;
 use App\Domains\Admin\Controllers\TenantListApiController;
 use App\Domains\Admin\Controllers\TenantPaymentGetController;
-use App\Domains\Admin\Controllers\TenantPaymentUpdateController;
 use App\Domains\Admin\Controllers\TenantPaymentMethodsGetController;
 use App\Domains\Admin\Controllers\TenantPaymentMethodsUpdateController;
+use App\Domains\Admin\Controllers\TenantPaymentUpdateController;
+use App\Domains\Admin\Controllers\TenantTaxGetController;
+use App\Domains\Admin\Controllers\TenantTaxUpdateController;
+use App\Domains\Admin\Controllers\UserDetailGetController;
+use App\Domains\Admin\Controllers\UserListApiController;
+use App\Domains\Admin\Controllers\UserResetPasswordController;
+use App\Domains\Admin\Controllers\UserToggleActiveController;
+use App\Domains\Admin\Controllers\UserUpdateController;
 use App\Middleware\AdminRoleMiddleware;
 use App\Middleware\IdentifyTenant;
 use App\Middleware\LvOnlyMiddleware;
@@ -44,6 +48,8 @@ Route::middleware([IdentifyTenant::class, 'auth', AdminRoleMiddleware::class])->
         Route::post('/impress', TenantImpressUpdateController::class);
         Route::get('/gdpr', TenantGdprGetController::class);
         Route::post('/gdpr', TenantGdprUpdateController::class);
+        Route::get('/tax', TenantTaxGetController::class);
+        Route::post('/tax', TenantTaxUpdateController::class);
     });
 
     Route::prefix('api/v1/admin/users')->group(function () {
@@ -69,6 +75,8 @@ Route::middleware([IdentifyTenant::class, 'auth', AdminRoleMiddleware::class])->
                 Route::post('/impress', ManagedTenantImpressUpdateController::class);
                 Route::get('/gdpr', ManagedTenantGdprGetController::class);
                 Route::post('/gdpr', ManagedTenantGdprUpdateController::class);
+                Route::get('/tax', ManagedTenantTaxGetController::class);
+                Route::post('/tax', ManagedTenantTaxUpdateController::class);
             });
         });
     });

app/Domains/Admin/Views/Partials/TenantTaxInfo.vue

@@ -0,0 +1,223 @@
+<script setup>
+import {computed, ref} from 'vue';
+import {useAjax} from "../../../../../resources/js/components/ajaxHandler.js";
+import RichSelectBox from "../../../../Views/Components/RichSelectBox.vue";
+import {toast} from "vue3-toastify";
+
+const props = defineProps({
+    data: {
+        type: Object,
+        default: () => ({})
+    },
+})
+
+const {request} = useAjax()
+
+const editing = ref(false)
+
+const reasons = computed(() => props.data.exemption_reasons ?? [])
+
+const liableOptions = [
+    {value: '1', label: 'Ja – Umsatzsteuer wird erhoben'},
+    {value: '0', label: 'Nein – umsatzsteuerbefreit'},
+]
+
+const form = ref({
+    tax_liable: props.data.tax_liable ? '1' : '0',
+    vat_rate: props.data.vat_rate ?? 0,
+    tax_exemption_reason: props.data.tax_exemption_reason ?? '',
+    tax_exemption_note: props.data.tax_exemption_note ?? '',
+})
+
+const isLiable = computed(() => form.value.tax_liable === '1')
+const isCustomReason = computed(() => form.value.tax_exemption_reason === 'custom')
+
+const selectedReason = computed(
+    () => reasons.value.find(r => r.value === form.value.tax_exemption_reason) ?? null
+)
+
+// Vorschau des Pflichthinweises nach § 14 Abs. 4 Nr. 8 UStG, der später auf der Rechnung erscheint.
+const invoiceHint = computed(() => {
+    if (isLiable.value) {
+        return `Umsatzsteuerpflichtig – USt-Satz: ${form.value.vat_rate || 0} %`
+    }
+    if (isCustomReason.value) {
+        return form.value.tax_exemption_note?.trim() || '—'
+    }
+    return selectedReason.value?.text || '—'
+})
+
+const reasonLabel = computed(() => selectedReason.value?.label ?? '—')
+
+async function save() {
+    const saveUrl = props.data.saveEndpoint ?? '/api/v1/admin/tenant/tax'
+    const response = await request(saveUrl, {
+        method: 'POST',
+        body: {
+            tax_liable: isLiable.value,
+            vat_rate: Number(form.value.vat_rate) || 0,
+            tax_exemption_reason: isLiable.value ? null : form.value.tax_exemption_reason,
+            tax_exemption_note: form.value.tax_exemption_note,
+        },
+    })
+
+    if (response && response.status === 'success') {
+        toast.success(response.message)
+        editing.value = false
+    } else {
+        toast.error(response?.message ?? 'Fehler beim Speichern')
+    }
+}
+</script>
+
+<template>
+    <div v-if="!editing">
+        <table class="data-table">
+            <tr>
+                <th>Steuerpflicht</th>
+                <td>{{ isLiable ? 'Ja – Umsatzsteuer wird erhoben' : 'Nein – umsatzsteuerbefreit' }}</td>
+            </tr>
+            <tr v-if="isLiable">
+                <th>USt-Satz</th>
+                <td>{{ form.vat_rate || 0 }} %</td>
+            </tr>
+            <tr v-else>
+                <th>Befreiungsgrund</th>
+                <td>{{ reasonLabel }}</td>
+            </tr>
+            <tr>
+                <th>Rechnungshinweis</th>
+                <td>{{ invoiceHint }}</td>
+            </tr>
+        </table>
+        <button class="btn-edit" @click="editing = true">Bearbeiten</button>
+    </div>
+
+    <div v-else>
+        <table class="data-table">
+            <tr>
+                <th>Steuerpflicht</th>
+                <td>
+                    <RichSelectBox v-model="form.tax_liable" :options="liableOptions"/>
+                </td>
+            </tr>
+
+            <tr v-if="isLiable">
+                <th>USt-Satz (%)</th>
+                <td><input type="number" min="0" max="100" v-model.number="form.vat_rate" class="form-input"/></td>
+            </tr>
+
+            <template v-else>
+                <tr>
+                    <th>Befreiungsgrund</th>
+                    <td>
+                        <RichSelectBox
+                            v-model="form.tax_exemption_reason"
+                            :options="reasons"
+                            placeholder="Grund auswählen…"
+                        />
+                    </td>
+                </tr>
+                <tr v-if="isCustomReason">
+                    <th>Freitext</th>
+                    <td>
+                        <textarea
+                            v-model="form.tax_exemption_note"
+                            class="form-input"
+                            rows="3"
+                            placeholder="Hinweistext für die Rechnung…"
+                        ></textarea>
+                    </td>
+                </tr>
+            </template>
+
+            <tr>
+                <th>Rechnungshinweis</th>
+                <td class="hint-preview">{{ invoiceHint }}</td>
+            </tr>
+        </table>
+        <div class="btn-group">
+            <button class="btn-save" @click="save">Speichern</button>
+            <button class="btn-cancel" @click="editing = false">Abbrechen</button>
+        </div>
+    </div>
+</template>
+
+<style scoped>
+.data-table {
+    width: 100%;
+    border-collapse: collapse;
+}
+
+.data-table th {
+    text-align: left;
+    padding: 8px 12px;
+    width: 200px;
+    color: #374151;
+    border-bottom: 1px solid #e5e7eb;
+    vertical-align: top;
+}
+
+.data-table td {
+    padding: 8px 12px;
+    border-bottom: 1px solid #e5e7eb;
+}
+
+.form-input {
+    width: 100%;
+    padding: 6px 10px;
+    border: 1px solid #d1d5db;
+    border-radius: 6px;
+    font-size: 0.95rem;
+    box-sizing: border-box;
+    font-family: inherit;
+}
+
+.hint-preview {
+    color: #6b7280;
+    font-style: italic;
+}
+
+.btn-edit, .btn-save, .btn-cancel {
+    margin-top: 15px;
+    padding: 8px 20px;
+    border: none;
+    border-radius: 6px;
+    cursor: pointer;
+    font-weight: bold;
+    font-size: 0.9rem;
+}
+
+.btn-edit {
+    background-color: #1d4899;
+    color: #ffffff;
+}
+
+.btn-edit:hover {
+    background-color: #163a7a;
+}
+
+.btn-save {
+    background-color: #16a34a;
+    color: #ffffff;
+}
+
+.btn-save:hover {
+    background-color: #15803d;
+}
+
+.btn-cancel {
+    background-color: #e5e7eb;
+    color: #374151;
+    margin-left: 10px;
+}
+
+.btn-cancel:hover {
+    background-color: #d1d5db;
+}
+
+.btn-group {
+    display: flex;
+    gap: 10px;
+}
+</style>

app/Domains/Admin/Views/TenantData.vue

@@ -7,6 +7,7 @@ import TenantPayment from "./Partials/TenantPayment.vue";
 import TenantImpress from "./Partials/TenantImpress.vue";
 import TenantGdpr from "./Partials/TenantGdpr.vue";
 import TenantPaymentMethods from "./Partials/TenantPaymentMethods.vue";
+import TenantTaxInfo from "./Partials/TenantTaxInfo.vue";
 
 const props = defineProps({
     tenant: Object,
@@ -28,6 +29,11 @@ const tabs = [
         component: TenantPaymentMethods,
         endpoint: '/api/v1/admin/tenant/payment-methods',
     },
+    {
+        title: 'Steuerinformationen',
+        component: TenantTaxInfo,
+        endpoint: '/api/v1/admin/tenant/tax',
+    },
     {
         title: 'Impressum',
         component: TenantImpress,

app/Domains/Admin/Views/TenantEdit.vue

@@ -7,6 +7,7 @@ import TenantContact from "./Partials/TenantContact.vue";
 import TenantPayment from "./Partials/TenantPayment.vue";
 import TenantImpress from "./Partials/TenantImpress.vue";
 import TenantGdpr from "./Partials/TenantGdpr.vue";
+import TenantTaxInfo from "./Partials/TenantTaxInfo.vue";
 
 const props = defineProps({
     tenant: Object,
@@ -30,6 +31,11 @@ const tabs = [
         component: TenantPayment,
         endpoint: '/api/v1/admin/tenants/' + slug + '/payment',
     },
+    {
+        title: 'Steuerinformationen',
+        component: TenantTaxInfo,
+        endpoint: '/api/v1/admin/tenants/' + slug + '/tax',
+    },
     {
         title: 'Impressum',
         component: TenantImpress,

app/Enumerations/TaxExemptionReason.php

@@ -0,0 +1,67 @@
+<?php
+
+namespace App\Enumerations;
+
+/**
+ * Gründe für eine Umsatzsteuerbefreiung. Jeder Fall kapselt sein UI-Label und den auf der Rechnung
+ * verpflichtenden Hinweis nach § 14 Abs. 4 Nr. 8 UStG, damit Label und Text nur an einer Stelle
+ * gepflegt werden. Gemeinnützigkeit allein befreit nicht – die Befreiung braucht immer einen konkreten
+ * Rechtsgrund; die Vereins-Fälle sind über § 4 Nr. 22a / Nr. 25 abgedeckt.
+ */
+enum TaxExemptionReason: string
+{
+    case SmallBusiness = 'small_business';
+    case Education = 'education';
+    case YouthWelfare = 'youth_welfare';
+    case Custom = 'custom';
+
+    public function label(): string
+    {
+        return match ($this) {
+            self::SmallBusiness => 'Kleinunternehmer (§ 19 UStG)',
+            self::Education => 'Bildungs-/Kursleistung (§ 4 Nr. 22a UStG)',
+            self::YouthWelfare => 'Kinder- und Jugendhilfe (§ 4 Nr. 25 UStG)',
+            self::Custom => 'Sonstiger Grund (Freitext)',
+        };
+    }
+
+    /**
+     * Pflichthinweis für die Rechnung. Bei einem individuellen Grund (Custom) wird der hinterlegte
+     * Freitext des Tenants verwendet.
+     */
+    public function invoiceText(?string $customNote = null): string
+    {
+        return match ($this) {
+            self::SmallBusiness => 'Gemäß § 19 UStG wird keine Umsatzsteuer berechnet.',
+            self::Education => 'Die Leistung ist gemäß § 4 Nr. 22 Buchst. a UStG von der Umsatzsteuer befreit.',
+            self::YouthWelfare => 'Die Leistung ist gemäß § 4 Nr. 25 UStG von der Umsatzsteuer befreit.',
+            self::Custom => trim((string)$customNote),
+        };
+    }
+
+    /**
+     * Ob dieser Grund einen zusätzlichen Freitext des Tenants erfordert.
+     */
+    public function requiresNote(): bool
+    {
+        return $this === self::Custom;
+    }
+
+    /**
+     * Optionen für das Frontend inkl. Vorschau-Text. Bei Custom ist `text` leer, da der Text erst aus
+     * dem Freitext des Tenants entsteht.
+     *
+     * @return array<int, array{value: string, label: string, text: string}>
+     */
+    public static function options(): array
+    {
+        return array_map(
+            static fn(self $reason): array => [
+                'value' => $reason->value,
+                'label' => $reason->label(),
+                'text' => $reason->requiresNote() ? '' : $reason->invoiceText(),
+            ],
+            self::cases(),
+        );
+    }
+}

app/Models/Tenant.php

@@ -21,6 +21,10 @@ use App\Scopes\CommonModel;
  * @property string $url_participation_rules
  * @property boolean $events_allowed
  * @property boolean $has_active_instance
+ * @property boolean $tax_liable
+ * @property int $vat_rate
+ * @property string|null $tax_exemption_reason
+ * @property string|null $tax_exemption_note
  */
 class Tenant extends CommonModel
 {
@@ -46,6 +50,15 @@ class Tenant extends CommonModel
         'impress_text',
         'url_participation_rules',
         'is_active_local_group',
-        'has_active_instance'
+        'has_active_instance',
+        'tax_liable',
+        'vat_rate',
+        'tax_exemption_reason',
+        'tax_exemption_note',
+    ];
+
+    protected $casts = [
+        'tax_liable' => 'boolean',
+        'vat_rate' => 'integer',
     ];
 }

database/migrations/2026_08_06_150000_add_tax_information_to_tenants.php

@@ -0,0 +1,29 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration {
+    public function up(): void
+    {
+        Schema::table('tenants', function (Blueprint $table) {
+            $table->boolean('tax_liable')->default(false);
+            $table->unsignedTinyInteger('vat_rate')->default(0);
+            $table->string('tax_exemption_reason')->default('youth_welfare');
+            $table->text('tax_exemption_note')->nullable();
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('tenants', function (Blueprint $table) {
+            $table->dropColumn([
+                'tax_liable',
+                'vat_rate',
+                'tax_exemption_reason',
+                'tax_exemption_note',
+            ]);
+        });
+    }
+};

tests/Feature/TenantTaxInformationTest.php

@@ -0,0 +1,119 @@
+<?php
+
+namespace Tests\Feature;
+
+use App\Domains\Admin\Actions\UpdateTenantTax\UpdateTenantTaxAction;
+use App\Domains\Admin\Actions\UpdateTenantTax\UpdateTenantTaxRequest;
+use App\Enumerations\TaxExemptionReason;
+use App\Models\Tenant;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+
+class TenantTaxInformationTest extends TestCase
+{
+    use RefreshDatabase;
+
+    private Tenant $tenant;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->tenant = Tenant::create([
+            'slug' => 'tv',
+            'name' => 'Test',
+            'email' => 't@example.com',
+            'email_finance' => 'finance@example.com',
+            'url' => 'test.local',
+            'account_name' => 'Test e.V.',
+            'account_iban' => 'DE00',
+            'account_bic' => 'XY',
+            'city' => 'Stadt',
+            'postcode' => '00000',
+            'is_active_local_group' => true,
+            'has_active_instance' => true,
+        ]);
+
+        app()->instance('tenant', $this->tenant);
+    }
+
+    private function runAction(bool $taxLiable, int $vatRate, ?string $reason, ?string $note = null): object
+    {
+        return new UpdateTenantTaxAction(new UpdateTenantTaxRequest(
+            tenant: $this->tenant,
+            taxLiable: $taxLiable,
+            vatRate: $vatRate,
+            exemptionReason: $reason,
+            exemptionNote: $note,
+        ))->execute();
+    }
+
+    public function test_taxable_sets_rate_and_clears_exemption(): void
+    {
+        $this->tenant->update(['tax_exemption_reason' => 'small_business', 'tax_exemption_note' => 'alt']);
+
+        $response = $this->runAction(taxLiable: true, vatRate: 7, reason: null);
+
+        $this->assertTrue($response->success);
+
+        $fresh = $this->tenant->fresh();
+        $this->assertTrue($fresh->tax_liable);
+        $this->assertSame(7, $fresh->vat_rate);
+        $this->assertNull($fresh->tax_exemption_reason);
+        $this->assertNull($fresh->tax_exemption_note);
+    }
+
+    public function test_exemption_reason_persists_and_clears_rate(): void
+    {
+        $response = $this->runAction(taxLiable: false, vatRate: 19, reason: 'youth_welfare');
+
+        $this->assertTrue($response->success);
+
+        $fresh = $this->tenant->fresh();
+        $this->assertFalse($fresh->tax_liable);
+        $this->assertSame(0, $fresh->vat_rate);
+        $this->assertSame('youth_welfare', $fresh->tax_exemption_reason);
+        $this->assertNull($fresh->tax_exemption_note);
+    }
+
+    public function test_invalid_exemption_reason_fails(): void
+    {
+        $response = $this->runAction(taxLiable: false, vatRate: 0, reason: 'not_a_reason');
+
+        $this->assertFalse($response->success);
+        $this->assertNull($this->tenant->fresh()->tax_exemption_reason);
+    }
+
+    public function test_custom_reason_requires_note(): void
+    {
+        $missing = $this->runAction(taxLiable: false, vatRate: 0, reason: 'custom', note: '  ');
+        $this->assertFalse($missing->success);
+
+        $ok = $this->runAction(taxLiable: false, vatRate: 0, reason: 'custom', note: 'Individueller Grund');
+        $this->assertTrue($ok->success);
+        $this->assertSame('Individueller Grund', $this->tenant->fresh()->tax_exemption_note);
+    }
+
+    public function test_vat_rate_is_clamped(): void
+    {
+        $this->runAction(taxLiable: true, vatRate: 250, reason: null);
+        $this->assertSame(100, $this->tenant->fresh()->vat_rate);
+    }
+
+    public function test_enum_invoice_text_per_case(): void
+    {
+        $this->assertSame(
+            'Gemäß § 19 UStG wird keine Umsatzsteuer berechnet.',
+            TaxExemptionReason::SmallBusiness->invoiceText(),
+        );
+        $this->assertSame(
+            'Die Leistung ist gemäß § 4 Nr. 22 Buchst. a UStG von der Umsatzsteuer befreit.',
+            TaxExemptionReason::Education->invoiceText(),
+        );
+        $this->assertSame(
+            'Die Leistung ist gemäß § 4 Nr. 25 UStG von der Umsatzsteuer befreit.',
+            TaxExemptionReason::YouthWelfare->invoiceText(),
+        );
+        $this->assertSame('Mein Text', TaxExemptionReason::Custom->invoiceText('Mein Text'));
+    }
+}