diff --git a/README.md b/README.md
index 96d5135..be449b7 100644
--- a/README.md
+++ b/README.md
@@ -451,7 +451,8 @@ Struct: `usecase.LoaFormRequest` (`internal/interfaces/usecase/loa.go:20`)
     "product_type": "Jcb Platinum",
     "cc_image_slim": "http://.../card/jcb_platinum_slim.png",
     "minimum_loan": 1000000,
-    "maximum_loan": 20000000
+    "maximum_loan": 20000000,
+    "loan_multiplier": 100000
   }
 }
 ```
@@ -460,6 +461,8 @@ Struct: `usecase.LoaFormRequest` (`internal/interfaces/usecase/loa.go:20`)
 
 `data` is `usecase.LoaFormResponse` (`internal/interfaces/usecase/loa.go:30`).
 
+> **Frontend validation:** the user-entered `amount` must be a multiple of `loan_multiplier` (e.g. if `100000`, only values like `100000`, `200000`, `1500000`, … are accepted).
+
 ### Error Codes
 
 | Code | When |