You do not need an auditor to audit accounts payable, and running the review yourself once a year is one of the cheapest pieces of assurance available to a small business. The checks are not sophisticated. They are the ones an auditor would run, applied to your own ledger by somebody who already knows where the awkward areas are, and they find the same things: duplicates, suppliers nobody recognises, approvals that never happened, and balances that have sat for two years because nobody wanted to write them off. This page is six checks you can run in an afternoon, in the order that finds the most for the least effort.
Start with duplicates and dormant balances
Sort by amount and by supplier and look for the same value twice, and for credit balances and very old items. Duplicate payments are recoverable if found, and old balances are either a supplier who will eventually ask or a write-back nobody has taken.
Then the supplier list itself
Suppliers added in the last year, suppliers with bank details changed, and suppliers whose address matches an employee's. Fictitious suppliers and diverted payments are standard payables frauds, and the ACFE's own material describes how ordinary the schemes are. A person simply reading the list catches most of it.
Then approvals, matching and the reconciliation
Sample twenty invoices and trace each approval. Check that matching exceptions were cleared by somebody who could answer them. Confirm the ledger reconciles to the control account. If those three hold, the population is probably sound.
Questions people ask about audit accounts payable
How often should we do this?
Annually is enough for most small businesses, plus after any change of staff in payables. The supplier list check is quick enough to do quarterly.
Who should run it?
Ideally not the person who processes the invoices. Where the team is too small, an owner or director running the supplier and duplicate checks is the compensating control.
What if we find something?
Duplicates are usually recoverable and worth pursuing. Anything suggesting a diverted payment stops being a finance exercise immediately and becomes a conversation with the owners and, likely, professional advice.