diff --git a/backend/tools/SorobanInvokeTool.ts b/backend/tools/SorobanInvokeTool.ts
index 914b4f6..7dc8c6b 100644
--- a/backend/tools/SorobanInvokeTool.ts
+++ b/backend/tools/SorobanInvokeTool.ts
@@ -11,7 +11,6 @@ import {
   TransactionBuilder,
   Operation,
   Contract,
-  BASE_FEE,
   nativeToScVal,
   xdr,
 } from "@stellar/stellar-sdk";
@@ -192,7 +191,7 @@ export class SorobanInvokeTool {
 
     // 3. Build invocation transaction
     const tx = new TransactionBuilder(sourceAccount, {
-      fee: BASE_FEE,
+      fee: "0", // Fee is overwritten by prepareSorobanTx — initial value is irrelevant
       networkPassphrase: this.networkPassphrase,
     })
       .addOperation(contract.call(input.method, ...input.args))
diff --git a/backend/tools/StellarPaymentTool.ts b/backend/tools/StellarPaymentTool.ts
index 817d450..f54cc07 100644
--- a/backend/tools/StellarPaymentTool.ts
+++ b/backend/tools/StellarPaymentTool.ts
@@ -126,7 +126,7 @@ export class StellarPaymentTool {
     // 4. Build transaction
     const buildTx = () => {
       const builder = new TransactionBuilder(sourceAccount, {
-        fee: BASE_FEE,
+        fee: BASE_FEE, // BASE_FEE (100 stroops) is the actual fee for classic Stellar payments — not overwritten
         networkPassphrase: this.networkPassphrase,
       })
         .addOperation(