diff --git a/services/nginx/app/objects/collected_order_invoices_o.php b/services/nginx/app/objects/collected_order_invoices_o.php
index d8bbf29c..02736df6 100644
--- a/services/nginx/app/objects/collected_order_invoices_o.php
+++ b/services/nginx/app/objects/collected_order_invoices_o.php
@@ -6,7 +6,13 @@ use classes\db;
 use classes\economic;
 use classes\object_property;
 use classes\stripe;
+use config\economic_admin_fee_monthly_c;
+use config\economic_admin_fee_order_c;
+use config\economic_fee_product_id_c;
 use Exception;
+use objects\order_items_o;
+use objects\orders_o;
+use objects\users_o;
 use Stripe\Exception\ApiErrorException;
 use traits\db_object_t;
 
@@ -422,6 +428,9 @@ class collected_order_invoices_o extends db
             self::requireOpen();
         }
 
+        // Ensure the administration fee is added to the invoice collection
+        self::ensureAdministrationFee();
+
         // Create an economic draft
         self::createInvoiceDraft();
 
@@ -680,6 +689,88 @@ class collected_order_invoices_o extends db
         }
     }
 
+    /**
+     * Ensure that the administration fee is added to the invoice collection, if it has not already been paid this month.
+     * @return void
+     * @throws Exception
+     */
+    public function ensureAdministrationFee(): void
+    {
+        // Require the invoice collection to be selected
+        self::requireSelected();
+        // Get the user object
+        $user = (new users_o())->getUserByCustomerNumber($this->customer_number->value());
+        // Check if the user has already paid the administration fee this month
+        if (self::hasPaidAdministrationFeeThisMonth()) {
+            return;
+        }
+
+        // Get the fee product ID
+        $fee_product_id = (int)(new economic_fee_product_id_c())->getVariableValue();
+        // Get the fee price
+        if ($user->invoicePerOrder()) {
+            $price = (int)(new economic_admin_fee_order_c())->getVariableValue();
+        } else {
+            $price = (int)(new economic_admin_fee_monthly_c())->getVariableValue();
+        }
+
+        // Add the fee order
+        $order = (new orders_o())->add(
+            (int)$user->id,
+            1857,
+            'Administrations og miljøtillæg',
+            '',
+            10,
+            '',
+            '',
+            ''
+        );
+        // Assign the order to the invoice collection
+        $order->assignToInvoiceCollection($this->id);
+        // Add the order item
+        (new order_items_o())->addItemToOrder(
+            (int)$order->id,
+            $fee_product_id,
+            1857,
+            1,
+            null,
+            '',
+            $price
+        );
+    }
+
+    /**
+     * Check if the customer has already paid the administration fee this month
+     * @return bool
+     * @throws Exception
+     */
+    public function hasPaidAdministrationFeeThisMonth(): bool
+    {
+        global $db;
+        // Require the invoice collection to be selected
+        self::requireSelected();
+        // Get the customer number
+        $customer_number = (int)$this->customer_number->value();
+        // Get the fee product ID
+        $fee_product_id = (int)(new economic_fee_product_id_c())->getVariableValue();
+        // Get the first and last day of the month
+        $first_day_of_month = date('Y-m-01 00:00:00');
+        $last_day_of_month = date('Y-m-t 23:59:59');
+        // Check if the customer has already paid the fee this month
+        $sql = "SELECT COUNT(*) as count 
+                FROM order_items oi
+                JOIN orders o ON oi.order_id = o.id
+                JOIN users u ON o.customer_id = u.id
+                WHERE u.customer_number = $customer_number
+                AND oi.product_id = $fee_product_id
+                AND o.created_at BETWEEN '$first_day_of_month' AND '$last_day_of_month'
+                AND o.deleted_at IS NULL";
+        // Execute the query
+        $result = $db->query($sql);
+        $row = $result->fetch_assoc();
+        return (int)$row['count'] > 0;
+    }
+
     /**
      * Require the invoice collection to not be booked
      * @throws Exception If the request was not successful