diff --git a/functions/src/domain/surcharge/helpers/rateCalculatorHelper.ts b/functions/src/domain/surcharge/helpers/rateCalculatorHelper.ts
index d166651..e27e59d 100644
--- a/functions/src/domain/surcharge/helpers/rateCalculatorHelper.ts
+++ b/functions/src/domain/surcharge/helpers/rateCalculatorHelper.ts
@@ -1,19 +1,14 @@
 export function rateCalculatorHelper(
-  rate: number | undefined, 
   totalAmount: number, 
   surchargeAmount: number
 ): number { 
-  if (typeof rate === 'undefined' || rate <= 0) {
-    throw new Error('Invalid input: rate amount must be greater than 0.');
-  } else {
-    if (surchargeAmount <= 0 || totalAmount <= 0) {
-      throw new Error('Invalid input: surchargeAmount and totalAmount must be greater than 0.');
-    }
-    const purchaseAmount = totalAmount - surchargeAmount
-    if (purchaseAmount <= 0) {
-      throw new Error('Invalid input: purchaseAmount amount must be greater than 0.');
-    }
-    const rate = (surchargeAmount / purchaseAmount) * 100
-    return Number(rate.toFixed(1))
+  if (surchargeAmount <= 0 || totalAmount <= 0) {
+    throw new Error('Invalid input: surchargeAmount and totalAmount must be greater than 0.');
   }
+  const purchaseAmount = totalAmount - surchargeAmount
+  if (purchaseAmount <= 0) {
+    throw new Error('Invalid input: purchaseAmount amount must be greater than 0.');
+  }
+  const rate = (surchargeAmount / purchaseAmount) * 100
+  return Number(rate.toFixed(1))
 }
diff --git a/functions/src/domain/surcharge/put/putSurchargeUsecase.ts b/functions/src/domain/surcharge/put/putSurchargeUsecase.ts
index 1371fb4..8e5f419 100644
--- a/functions/src/domain/surcharge/put/putSurchargeUsecase.ts
+++ b/functions/src/domain/surcharge/put/putSurchargeUsecase.ts
@@ -11,7 +11,6 @@ export const putSurchargeUsecase = async (
 
   if (request.totalAmount && request.surchargeAmount) {
     newRate = rateCalculatorHelper(
-      undefined,
       request.totalAmount,
       request.surchargeAmount
     );