Which of the following represents the best method for confirming that vendor invoices were for...

A. Vouching vendor invoices to payments made:This verifies payment accuracy but does not confirm whether purchases were authorized.

B. Sorting invoices by purchase orders and comparing for successive duplicate invoices:This approach focuses on detecting duplicate invoices, not authorization.

C. Comparing a random sample of vendor invoices to purchase orders:Correct. This method directly matches invoices to purchase orders, confirming that purchases were authorized and appropriately documented.

D. Sorting payments by invoice to detect successive duplicate invoices:Similar to option B, this approach focuses on detecting duplicates rather than verifying authorization.

CIA Exam Syllabus Reference:

Domain V: Performing Internal Audit Services – Testing for Authorization and Validity.