diff --git a/openapi.yaml b/openapi.yaml
index 1be1b5a5..aa598aac 100644
--- a/openapi.yaml
+++ b/openapi.yaml
@@ -18548,11 +18548,13 @@ components:
           additionalProperties:
             type: array
             items:
-              $ref: '#/components/schemas/InvoicingPeriodCustomer'
+              oneOf:
+                - $ref: '#/components/schemas/InvoicingPeriodCustomer'
+                - $ref: '#/components/schemas/InvoicingPeriodCustomerMembership'
 
     InvoicingPeriodCustomer:
       type: object
-      required: [customer_number, customer_name, transactions, invoice_collections]
+      required: [customer_number]
       additionalProperties: true
       properties:
         customer_number:
@@ -18568,6 +18570,27 @@ components:
           items:
             $ref: '#/components/schemas/InvoicingPeriodInvoiceCollection'
 
+    InvoicingPeriodCustomerMembership:
+      type: object
+      description: >-
+        Lightweight customer marker returned for every non-active view
+        bucket of the period response. Used by the front-end to render
+        category indicator chips (e.g. "Faktura pr. ordre") regardless of
+        which tab the user is currently looking at. Full customer-card
+        data (transactions, invoice collections, queue, draft, meta)
+        is intentionally omitted for non-active buckets; see
+        InvoicingPeriodCustomer for the shape returned for the active
+        bucket.
+      additionalProperties: false
+      required: [customer_number, membership_only]
+      properties:
+        customer_number:
+          type: integer
+          minimum: 1
+        membership_only:
+          type: boolean
+          enum: [true]
+
     InvoicingPeriodTransaction:
       type: object
       required: [id, booked, invoice_state]
diff --git a/services/nginx/app/routes/InvoicingPeriodRoute.php b/services/nginx/app/routes/InvoicingPeriodRoute.php
index c094b83f..0119eb6c 100644
--- a/services/nginx/app/routes/InvoicingPeriodRoute.php
+++ b/services/nginx/app/routes/InvoicingPeriodRoute.php
@@ -739,6 +739,22 @@ class InvoicingPeriodRoute
             $pagedTypes[$periodView] = array_slice($types[$periodView], $offset, $perPage);
         }
 
+        // Surface lightweight customer memberships for every non-active
+        // view bucket so the front-end can render category indicator
+        // chips (e.g. "Faktura pr. ordre") regardless of which tab the
+        // user is currently looking at. Filters, search, sort, flag tab
+        // and workflow filters have already been applied to `$types`
+        // above, so the membership set matches the active bucket's
+        // semantics for this request.
+        foreach ($types as $typeName => $customers) {
+            if ($typeName === $periodView) {
+                continue;
+            }
+            $pagedTypes[$typeName] = self::summarizePeriodCustomerMemberships(
+                is_array($customers) ? $customers : []
+            );
+        }
+
         $period['types'] = $pagedTypes;
         $period['type_counts'] = $typeCounts;
         $period['type_totals'] = self::summarizePeriodTypeTotals($types);
@@ -1230,6 +1246,41 @@ class InvoicingPeriodRoute
         return $counts;
     }
 
+    /**
+     * Build a deduplicated list of lightweight `{customer_number}` markers
+     * for a single non-active view bucket. These entries let the front-end
+     * know which customers belong to a category without shipping the full
+     * card (transactions, invoice_collections, queue, draft, meta, …).
+     *
+     * Filters, search, sort, flag tab and workflow filters are expected to
+     * have been applied to `$customers` upstream — we only de-duplicate and
+     * project the `customer_number` field here.
+     *
+     * @param array<int, array<string, mixed>> $customers
+     * @return array<int, array{customer_number: int, membership_only: true}>
+     */
+    private static function summarizePeriodCustomerMemberships(array $customers): array
+    {
+        $memberships = [];
+        $seen = [];
+        foreach ($customers as $customer) {
+            if (!is_array($customer)) {
+                continue;
+            }
+            $customerNumber = (int)($customer['customer_number'] ?? 0);
+            if ($customerNumber < 1 || isset($seen[$customerNumber])) {
+                continue;
+            }
+            $seen[$customerNumber] = true;
+            $memberships[] = [
+                'customer_number' => $customerNumber,
+                'membership_only' => true,
+            ];
+        }
+
+        return $memberships;
+    }
+
     private static function summarizePeriodTypeTotals(array $types): array
     {
         $totals = [];
diff --git a/services/nginx/app/tests/Unit/Invoicing/InvoicingPeriodPaginationTest.php b/services/nginx/app/tests/Unit/Invoicing/InvoicingPeriodPaginationTest.php
index 39f190e7..0e4eca27 100644
--- a/services/nginx/app/tests/Unit/Invoicing/InvoicingPeriodPaginationTest.php
+++ b/services/nginx/app/tests/Unit/Invoicing/InvoicingPeriodPaginationTest.php
@@ -289,7 +289,9 @@ it('slices only the active period view and keeps exact full-result type counts',
         'po' => 'PO-BETA',
         'reg_1' => 'BB22222',
     ]);
-    expect($result['period']['types']['fixed_pricing'])->toBe([]);
+    expect($result['period']['types']['fixed_pricing'])->toBe([
+        ['customer_number' => 1002, 'membership_only' => true],
+    ]);
     expect($result['period']['type_counts']['all'])->toBe([
         'requires_action' => 1,
         'draft' => 1,
@@ -687,3 +689,219 @@ it('blocks review from aggregate manual counts when restricted flag details are
             'next_action' => 'resolve_manual_flags',
         ]);
 });
+
+it('surfaces lightweight customer memberships on every non-active period view bucket', function (): void {
+    $period = [
+        'dateFrom' => '2026-04-01 00:00:00',
+        'dateTo' => '2026-04-30 23:59:59',
+        'types' => [
+            'all' => [
+                invoicing_period_customer_card(2001, 'Alpha Logistics', [
+                    invoicing_period_transaction(['id' => 21, 'customer_number' => 2001, 'amount' => 100]),
+                ]),
+                invoicing_period_customer_card(2002, 'Beta Logistics', [
+                    invoicing_period_transaction(['id' => 22, 'customer_number' => 2002, 'amount' => 200]),
+                ]),
+                invoicing_period_customer_card(2003, 'Gamma Logistics', [
+                    invoicing_period_transaction(['id' => 23, 'customer_number' => 2003, 'amount' => 300]),
+                ]),
+            ],
+            'fixed_pricing' => [
+                invoicing_period_customer_card(2001, 'Alpha Logistics', [], false, [
+                    'meta' => ['fixed_pricing' => ['price' => 600]],
+                ]),
+            ],
+            'invoice_per_order' => [
+                invoicing_period_customer_card(2002, 'Beta Logistics', [], true),
+                invoicing_period_customer_card(2002, 'Beta Logistics', [], true),
+            ],
+            'tank_cleaning' => [
+                invoicing_period_customer_card(2003, 'Gamma Logistics', [], false),
+            ],
+            'vehicle_subscriptions' => [],
+            'special_arrangements' => [],
+            'possible_duplicates' => [],
+            'self_wash' => [],
+        ],
+    ];
+
+    $result = invoicing_period_pagination_invoke('applyPeriodPagination', [$period, [
+        'periodView' => 'all',
+        'page' => 1,
+        'limit' => 25,
+        'includeRequiresAction' => true,
+        'includeBooked' => true,
+    ]]);
+
+    // Active bucket still carries full customer cards.
+    expect($result['period']['types']['all'])->toHaveCount(3);
+    expect($result['period']['types']['all'][0])->toHaveKey('transactions');
+    expect($result['period']['types']['all'][0])->toHaveKey('customer_name');
+
+    // Non-active buckets expose only {customer_number, membership_only: true} entries.
+    expect($result['period']['types']['fixed_pricing'])->toBe([
+        ['customer_number' => 2001, 'membership_only' => true],
+    ]);
+    // Membership entries must de-duplicate by customer_number even when the
+    // source bucket contains the customer twice.
+    expect($result['period']['types']['invoice_per_order'])->toBe([
+        ['customer_number' => 2002, 'membership_only' => true],
+    ]);
+    expect($result['period']['types']['tank_cleaning'])->toBe([
+        ['customer_number' => 2003, 'membership_only' => true],
+    ]);
+
+    // Buckets with no matching customers stay as empty arrays.
+    expect($result['period']['types']['vehicle_subscriptions'])->toBe([]);
+    expect($result['period']['types']['special_arrangements'])->toBe([]);
+    expect($result['period']['types']['possible_duplicates'])->toBe([]);
+    expect($result['period']['types']['self_wash'])->toBe([]);
+
+    // Counts and totals remain authoritative and unaffected by pagination.
+    expect($result['period']['type_counts']['all']['total'])->toBe(3);
+    // summarizePeriodType counts raw array entries; the duplicate 2002 entry
+    // in invoice_per_order is therefore reflected in type_counts but our
+    // membership projector de-duplicates it (asserted above).
+    expect($result['period']['type_counts']['invoice_per_order']['total'])->toBe(2);
+    expect($result['period']['type_totals']['fixed_pricing']['total'])->toBe(600.0);
+});
+
+it('respects the search filter when emitting customer memberships on non-active buckets', function (): void {
+    $period = [
+        'dateFrom' => '2026-04-01 00:00:00',
+        'dateTo' => '2026-04-30 23:59:59',
+        'types' => [
+            'all' => [
+                invoicing_period_customer_card(3001, 'Alpha', [
+                    invoicing_period_transaction(['id' => 31, 'customer_number' => 3001, 'amount' => 10]),
+                ]),
+                invoicing_period_customer_card(3002, 'Beta', [
+                    invoicing_period_transaction(['id' => 32, 'customer_number' => 3002, 'amount' => 20]),
+                ]),
+                invoicing_period_customer_card(3003, 'Gamma', [
+                    invoicing_period_transaction(['id' => 33, 'customer_number' => 3003, 'amount' => 30]),
+                ]),
+            ],
+            'invoice_per_order' => [
+                invoicing_period_customer_card(3001, 'Alpha', [], true),
+                invoicing_period_customer_card(3003, 'Gamma', [], true),
+            ],
+            'fixed_pricing' => [
+                invoicing_period_customer_card(3002, 'Beta', [], false),
+                invoicing_period_customer_card(3003, 'Gamma', [], false),
+            ],
+        ],
+    ];
+
+    $result = invoicing_period_pagination_invoke('applyPeriodPagination', [$period, [
+        'periodView' => 'all',
+        'page' => 1,
+        'limit' => 25,
+        'search' => 'Beta',
+        'includeRequiresAction' => true,
+        'includeBooked' => true,
+    ]]);
+
+    expect(array_column($result['period']['types']['all'], 'customer_number'))->toBe([3002]);
+    expect($result['period']['types']['invoice_per_order'])->toBe([]);
+    expect($result['period']['types']['fixed_pricing'])->toBe([
+        ['customer_number' => 3002, 'membership_only' => true],
+    ]);
+});
+
+it('respects the flag-tab filter when emitting customer memberships on non-active buckets', function (): void {
+    $period = [
+        'dateFrom' => '2026-04-01 00:00:00',
+        'dateTo' => '2026-04-30 23:59:59',
+        'types' => [
+            'all' => [
+                invoicing_period_customer_card(4001, 'Red Flag Customer', [
+                    invoicing_period_transaction(['id' => 41, 'customer_number' => 4001, 'amount' => 50]),
+                ], false, [
+                    'flags' => [
+                        [
+                            'source' => 'manual',
+                            'status' => 'active',
+                            'target_type' => 'customer',
+                        ],
+                    ],
+                ]),
+                invoicing_period_customer_card(4002, 'Clean Customer', [
+                    invoicing_period_transaction(['id' => 42, 'customer_number' => 4002, 'amount' => 60]),
+                ], false),
+            ],
+            'invoice_per_order' => [
+                invoicing_period_customer_card(4001, 'Red Flag Customer', [], true, [
+                    'flags' => [
+                        [
+                            'source' => 'manual',
+                            'status' => 'active',
+                            'target_type' => 'customer',
+                        ],
+                    ],
+                ]),
+                invoicing_period_customer_card(4002, 'Clean Customer', [], true),
+            ],
+            'fixed_pricing' => [
+                invoicing_period_customer_card(4001, 'Red Flag Customer', [], true, [
+                    'flags' => [
+                        [
+                            'source' => 'manual',
+                            'status' => 'active',
+                            'target_type' => 'customer',
+                        ],
+                    ],
+                ]),
+                invoicing_period_customer_card(4002, 'Clean Customer', [], false),
+            ],
+        ],
+    ];
+
+    $result = invoicing_period_pagination_invoke('applyPeriodPagination', [$period, [
+        'periodView' => 'all',
+        'page' => 1,
+        'limit' => 25,
+        'flagTab' => 'red',
+        'includeRequiresAction' => true,
+        'includeBooked' => true,
+    ]]);
+
+    expect(array_column($result['period']['types']['all'], 'customer_number'))->toBe([4001]);
+    expect($result['period']['types']['invoice_per_order'])->toBe([
+        ['customer_number' => 4001, 'membership_only' => true],
+    ]);
+    expect($result['period']['types']['fixed_pricing'])->toBe([
+        ['customer_number' => 4001, 'membership_only' => true],
+    ]);
+});
+
+it('emits lightweight memberships on non-active buckets when the active bucket is a single customer', function (): void {
+    $period = [
+        'dateFrom' => '2026-04-01 00:00:00',
+        'dateTo' => '2026-04-30 23:59:59',
+        'types' => [
+            'all' => [
+                invoicing_period_customer_card(5001, 'Solo Customer', [
+                    invoicing_period_transaction(['id' => 51, 'customer_number' => 5001, 'amount' => 80]),
+                ]),
+            ],
+            'invoice_per_order' => [
+                invoicing_period_customer_card(5001, 'Solo Customer', [], true),
+            ],
+        ],
+    ];
+
+    $result = invoicing_period_pagination_invoke('applyPeriodPagination', [$period, [
+        'periodView' => 'invoice_per_order',
+        'page' => 1,
+        'limit' => 25,
+        'includeRequiresAction' => true,
+        'includeBooked' => true,
+    ]]);
+
+    expect($result['period']['types']['invoice_per_order'])->toHaveCount(1);
+    expect($result['period']['types']['invoice_per_order'][0])->toHaveKey('transactions');
+    expect($result['period']['types']['all'])->toBe([
+        ['customer_number' => 5001, 'membership_only' => true],
+    ]);
+});