diff --git a/src/pages/03_customer-management/form.ts b/src/pages/03_customer-management/form.ts
index 1cc7b126..1055546f 100644
--- a/src/pages/03_customer-management/form.ts
+++ b/src/pages/03_customer-management/form.ts
@@ -259,7 +259,8 @@ export const useCustomerForm = defineStore('form-customer', () => {
       telephoneNo:
         currentFormData.value.customerBranch?.at(0)?.telephoneNo || '',
       gender: currentFormData.value.customerBranch?.at(0)?.gender || '',
-      birthDate: currentFormData.value.customerBranch?.at(0)?.birthDate || '',
+      birthDate:
+        currentFormData.value.customerBranch?.at(0)?.birthDate || undefined,
 
       businessType:
         currentFormData.value.customerBranch?.at(0)?.businessType || '',