Tests of control or substantive procedures?

Most assertions can be tested through both. So, for purchases cut-off, for example:

1 Determine the system that the company uses to ensure, for example, that all goods received before year end have either been invoiced for or are accrued for. Large companies must have some sort of system, such as being able to idendify goods received notes that have no matching invoices. For several GRNs test that the system is operating (eg an employee physically pairs GRNs and invoices and any unpaired need an accrual) That is a test of control. Perhaps the employee stamps each unmatched GRN to show that it has been accrued for.

Alternatively in a computerised system, use test data. Submit some GRNs and invoices and ensure that the computer sets up the proper accruals where there is a GRN and no invoice. That would be testing a programmed procedure/control

2 Look at some receipts of goods close to year end and trace those either to invoices received before year end or to their appearance on an accruals schedule. That is a substantive test. Look at the list of GRNs accrued for and trace to invoices received after year end to ensure no double liability. Again this is a substantive test.