Subsequent payments testing is: 

(a) Vouching for a sample of payments made after year end to supporting invoices to ensure that amounts related to invoices dated prior to year end have been included in payables. 

(b) Vouching for a sample of cash receipts received after year end to supporting invoices to ensure that amounts related to invoices dated prior to year end have been included in payables. 

(c) Not required because the client would want to make sure that all payables are included as liabilities on the balance sheet. 

(d) Not required because the client would not pay an invoice that was not properly recorded.