diff --git a/lib/commission/payment.test.ts b/lib/commission/payment.test.ts
index 4caf91f..781cf5d 100644
--- a/lib/commission/payment.test.ts
+++ b/lib/commission/payment.test.ts
@@ -36,9 +36,10 @@ describe("commission slip verification", () => {
     const fetch = vi.fn(async (_url: URL, init: RequestInit) => {
       expect(init.headers).toEqual({ Authorization: "Bearer secret" });
       const payload = JSON.parse((init.body as FormData).get("payload") as string);
-      expect(payload).toMatchObject({ checkDuplicate: true,
+      expect(payload).toMatchObject({
         checkReceiver: [{ accountType: "02001", accountNumber: "0812345678" }],
         checkAmount: { type: "eq", amount: "100.00" } });
+      expect(payload).not.toHaveProperty("checkDuplicate");
       return Response.json(response);
     });
     vi.stubGlobal("fetch", fetch);
diff --git a/lib/commission/payment.ts b/lib/commission/payment.ts
index d15cad5..184487d 100644
--- a/lib/commission/payment.ts
+++ b/lib/commission/payment.ts
@@ -38,7 +38,6 @@ export async function verifyCommissionSlip(file: File, amountBaht: number, check
   const form = new FormData();
   form.set("file", file);
   form.set("payload", JSON.stringify({
-    checkDuplicate: true,
     checkReceiver: [{
       accountType: { mobile: "02001", nationalId: "02003", ewallet: "02004" }[identifier.type],
       accountNumber: receiverNumber,