After an accounting staff prepares a payment voucher, K Chayapat (Assistant Accounting Manager) reviews every payment voucher before an accounting staff submits to the system. She checks if payment transactions are properly prepared and approved by authorized persons, reasonable and being recorded in the proper period. Also, She checks details in payment vouchers with supporting documents such as purchase orders, invoices, and so on. Then, they sign off on the payment vouchers. This control takes place many times per day.