Two way matching in accounts payable is the invoice-against-order check, and whether you use it is a smaller question than whether anybody knows when it applies. Most small finance teams use two way matching for some spend and three way for the rest, which is sensible, and decide which is which invoice by invoice, which is not. The result is a control whose operation depends on who opened the post. This page is about writing the rule down: what a good matching rule looks like, how to express it in categories a non-specialist can apply, and why the written rule is worth more than the particular choice it encodes.
What a matching rule has to say
Which spend categories get which check, what the tolerances are, what happens to an invoice with no order, and who resolves an exception. Four sentences is usually enough, and four sentences that exist beat a sophisticated policy that lives in one person's judgement.
Express it in categories people recognise
Goods with a delivery, services with a contract, recurring subscriptions, and one-off spend below a threshold. Those are categories a new starter can apply on their first day, which is the actual test of a rule.
Why the written rule beats the choice
An auditor tests whether a control operated consistently, not whether it was the most rigorous available. A written two way matching rule applied every time is stronger evidence than an unwritten three way ambition applied when there is time.
Questions people ask about two way matching in accounts payable
Where should the rule live?
Somewhere an approver and a new starter will both find it, which usually means alongside the payables process rather than in a policy folder. A rule nobody can find is an unwritten rule with extra steps.
How detailed should it be?
Short enough to be read. Detail belongs in the exceptions register, where the awkward cases accumulate with what was decided, which is a more useful document than a longer policy.
Who owns it?
Whoever owns payables, with the budget holders having agreed the thresholds. Ownership matters because a rule with no owner is not reviewed when the supplier mix changes.