Inspect some of invoices and confirm if they are sequentially numbered And if the are flagged up? Can this be a substantive procedure or these are TOC?
A substantive procedure is concerned with monetary amounts ($) and provides direct evidence that amounts are correct. Monetary amounts are irrelevant to a test of control – for each item tested there are only two outcomes – either the control was applied – or it was not. So even if you did not know that sequence checking any documentation is a control to help ensure completeness (Chapter 14 – application control) – reperformance of a sequence check must be a test of control – the monetary amounts of the invoices are irrelevant.