diff --git a/src/api/subscription.ts b/src/api/subscription.ts
index 80b60dd..3e0de3b 100644
--- a/src/api/subscription.ts
+++ b/src/api/subscription.ts
@@ -103,6 +103,11 @@ export const subscriptionApi = {
     await apiClient.post('/cabinet/subscription/devices/save-cart', { devices });
   },
 
+  // Save traffic cart for later purchase after top-up
+  saveTrafficCart: async (trafficGb: number): Promise<void> => {
+    await apiClient.post('/cabinet/subscription/traffic/save-cart', { traffic_gb: trafficGb });
+  },
+
   // Update autopay settings
   updateAutopay: async (
     enabled: boolean,