A useful invoice audit checklist connects each question to a source record and a review decision. Start with the population, test the conditions that matter, and leave a clear path from an exception to its resolution.
Define the question before collecting invoices
Decide whether the review addresses payment approval, purchasing controls, recorded expenses or another objective. These objectives overlap, but they require different evidence. Correct multiplication supports the recorded amount. It does not establish that equipment arrived, that a manager authorized the purchase or that the expense belongs in the period.
Record the entity, period, source system and selection method. A review of unpaid invoices over $10,000 answers a narrower question than a review of all invoices posted during the quarter. Keep canceled documents, credits and excluded transaction types visible in the scope description so another reviewer can understand the population.
Build an evidence pack that can survive a handoff
Retain the original invoice, the export used for testing and the records needed for the chosen checks. Record the export time, filters, row count and relevant control totals. Reconcile the extract to the source report before treating its contents as the complete population. Preserve original document references alongside any cleaned values.
For audits under PCAOB standards, evidence must be relevant and reliable as well as sufficient. Using company-produced information requires attention to its accuracy, completeness and level of detail. A larger spreadsheet does not resolve those questions. See PCAOB AS 1105: Audit Evidence.
Use a checklist with explicit evidence and follow-up
| Review question | Evidence to inspect | Follow-up when it does not reconcile |
|---|---|---|
| Is the supplier appropriate for this purchase? | Vendor record, onboarding evidence and relevant status history. | Resolve identity or status differences; an active master record alone does not authenticate the supplier. |
| Does the invoice calculate correctly? | Quantities, unit prices, tax, discounts and stated total. | Trace the difference to a line or adjustment and obtain a corrected document where needed. |
| Was the purchase authorized? | Applicable policy, purchase order and approval history. | Distinguish a missing export reference from a purchase made without required approval. |
| Were the goods or services received? | Receiving records, accepted deliverables or approved service records. | Investigate partial delivery, disputed work or timing differences. |
| Is this obligation already recorded? | Invoice history, source documents, credits and payment status. | Investigate matching records before concluding there is a duplicate liability or payment. |
| Are the charges consistent with the agreement? | Executed contract, amendments, rate schedules and service period. | Resolve unsupported rates, scope differences and missing credits. |
Price and receipt checks deserve separate attention. Microsoft's invoice-matching guidance distinguishes comparing invoice prices with a purchase order from also comparing quantities with product receipts. That distinction helps explain why matching a PO reference is only one part of review. See Accounts payable invoice matching overview.
Work an exception through to a supported conclusion
The synthetic OpenAuditor supplier-invoice example concerns Northstar IT Supply invoice INV-2026-0841: 20 business laptops at $1,240 each, totaling $24,800. Tax and discount are zero. The supplied vendor record is active, but the invoice contains no purchase-order reference. The example uses the engine's default $1,000 PO threshold.
The recorded run, made with the local engine in the production configuration, confirms the arithmetic and fails the required-PO check. Its supplied comparison history is explicitly empty, so the duplicate check finds no match within that scope. That is not evidence that no duplicate exists elsewhere. The overall result is false because of the PO exception; the description judgment is not asked.
The reviewer now needs the purchasing record. If a timely approved PO exists and the export omitted its reference, correct the input and preserve both versions. If purchasing bypassed approval, adding a reference later does not establish that the control operated when required. Receiving evidence and the accounting entry remain separate work.
Keep transaction value, control threshold and materiality separate
The $24,800 is the value reviewed. The $1,000 threshold determines when this control requires a reference. Neither establishes a $24,800 misstatement. The laptops might have arrived and been recorded correctly even though purchasing authorization failed.
For PCAOB engagements, materiality depends on the engagement circumstances and includes quantitative and qualitative considerations. It is not obtained by copying an operational approval limit. See PCAOB AS 2105: Consideration of Materiality. Record the significance assessment and any identified accounting difference separately from the control finding.
Close the finding with evidence, ownership and a disposition
Give each open item an owner, the evidence requested and a response date. A response such as “approved by the department” needs the supporting approval record and its timing. Preserve contrary evidence as well as the explanation that ultimately supports the conclusion.
Use dispositions that explain what happened: input corrected, control exception confirmed, valid policy exception supported, accounting correction required or unresolved evidence request. Record the supporting documents, reviewer and resulting action. A valid policy exception needs its authority and rationale; it should not be hidden by changing the original test result.
Automate the repeatable checks within the wider review
OpenAuditor's financial invoice procedure checks supplied arithmetic, vendor status, duplicate criteria and the required PO reference. It does not inspect the underlying PO or independently confirm receipt. Use its findings to direct follow-up, with the source evidence and professional judgments retained in your own review record.
Start with the worked request and learn to read results and evidence pointers. Before dividing an invoice population into requests, inspect the experiment on batch boundaries and lost duplicate findings. For charges tied to an agreement, continue with contract invoice review. The audit concepts guide explains how these checks fit the objective of the engagement.