Accounts Payable Review

By Nupur Mittal

Co-founder at OCTA — works with accounting firms on month-end close and reconciliation automation.

An accounts payable review is the process of analyzing every outstanding vendor invoice by age and vendor, confirming payments are being made within agreed terms, and catching duplicate invoices, duplicate payments, and mismatches between what was ordered, received, and billed. It protects cash and vendor relationships by making sure the business pays what it owes — once, on time, and only for goods and services it actually received. This page walks through the full process step by step, the red flags a careful reviewer watches for, and how accounting firms run AP reviews faster with OCTA Flow while a human approves every action.

Why accounts payable review matters, and where it goes wrong

Accounts payable is one of the few ledgers where a mistake costs real cash immediately — not just a misstated balance that gets caught at close. Pay a vendor twice and the money is gone until someone notices and chases it back. Miss a genuine invoice for 120 days and a vendor relationship, or a discount, is at risk. Because AP volume scales with the business — dozens of vendors becomes hundreds, a handful of invoices a week becomes thousands a month — the review work that once took an afternoon can consume days, and the mechanical parts of it (aging, matching, terms-compliance math) crowd out the judgment calls that actually need a person.

The stakes are also asymmetric. A late payment is annoying; a duplicate payment or a payment made against goods never received is money out the door that has to be actively recovered. That is why AP review exists as a distinct, recurring control rather than something bundled quietly into close: it forces every outstanding invoice into an aging bucket, checks it against payment terms, and runs a set of fraud- and error-detection tests — duplicate invoices, duplicate payments, three-way match failures — before cash goes out the door, not after.

The accounts payable review process, step by step

A rigorous AP review follows a consistent sequence, whether it's done by a bookkeeper with a spreadsheet or a firm running it for a portfolio of clients. The steps below are the full procedure OCTA Flow executes; they also stand alone as a best-practice checklist any AP team can follow.

1. Establish the aging buckets. Set the period-end date and calculate days outstanding for every invoice from its invoice date to that date. The standard buckets are Current (0–30 days), 31–60 days, 61–90 days, and Over 90 days.

2. Analyze aging by vendor. For each vendor, total the outstanding balance, split it across the buckets, flag any vendor with a balance over 90 days, and compare the outstanding balance against that vendor's payment terms to catch breaches.

3. Identify overdue payments. Flag any invoice where days outstanding exceeds the vendor's agreed terms (default to a standard Net 30 if no vendor-specific terms are on file, and note that assumption). Treat the 61–90 day bucket as needing a scheduled payment, and treat anything over 90 days as high priority.

4. Check for duplicate invoices. Scan for the classic duplicate-invoice signatures: the same vendor, same amount, and same invoice date; the same vendor and amount within 7 days on different dates; the same invoice number appearing more than once; and round-dollar invoices over $10,000 from the same vendor within 30 days — a common pattern in erroneous or fraudulent re-billing.

5. Check for duplicate payments. Where payment history is available, look for the same vendor paid the same amount twice within 30 days, or a payment that references an invoice number already paid. This is the single most urgent finding in an AP review — flag it for immediate investigation and recovery, since the cash is already out the door.

6. Run the three-way match. Where purchase orders and goods-receipt data are available, match invoice to PO to goods receipt. Flag invoices with no matching PO (maverick spend), invoices billed for more than the PO amount (overbilling), and invoices where goods haven't yet been received but payment is being requested.

7. Reconcile credit notes. Identify credit notes from vendors that haven't been applied against outstanding invoices, flag any sitting unapplied for more than 30 days, and calculate the net AP balance after applying available credits.

8. Test payment terms compliance. Calculate the percentage of invoices paid within terms, the average days to pay by vendor, any early-payment discounts available but not taken, and the exposure to late-payment penalties where terms include them.

9. Summarize the cash flow impact. Roll the ledger up into what's due in the next 7 days, what's due in the next 30 days, what's already overdue, and what's disputed or on hold — the numbers a CFO actually needs for cash planning.

10. Check vendor concentration. Rank the top 10 vendors by outstanding balance and flag any single vendor representing more than 20% of total AP — a concentration risk worth a CFO's attention even when every invoice on file is legitimate.

Worked examples: AP aging buckets, a duplicate payment, and a three-way match

AP aging buckets

A month-end AP aging summary for a mid-size vendor ledger might look like this:

The 9% sitting over 90 days is the number a reviewer chases first — every invoice in that bucket needs either a payment plan, a documented dispute, or an explanation, because "over 90 and untouched" is the profile of both cash-flow risk and vendor-relationship risk.

A duplicate payment

Payment history for the period shows two payments to the same vendor:

Same vendor, same invoice number, same amount, paid twice 15 days apart — a textbook duplicate payment. This is flagged critical and routed for immediate recovery: the AP team contacts the vendor, confirms the second payment was in error, and initiates a refund or credit against the next invoice. The finding is never quietly written off; $6,150 in cash is missing until it's actively recovered.

A three-way match failure

An invoice comes in for review against its purchase order and goods receipt:

The invoice is $1,850 above the approved PO amount — an overbilling flag. Because the goods receipt confirms the full order was delivered, the finding routes to the vendor with a request to explain or credit the $1,850 difference before payment is released, rather than paying the invoice as billed.

Key controls and red flags

The difference between an aging report and a genuine AP review is what a reviewer actively tests for. A rigorous review flags:

• Duplicate payments — same vendor, same amount, paid twice within 30 days — the most urgent finding, since cash is already gone
• Duplicate invoices — matching invoice numbers, or the same vendor/amount/date combination appearing more than once
• Invoices outstanding more than 90 days with no documented dispute or payment plan
• Three-way match failures — no matching PO (maverick spend), invoice amount above the PO amount (overbilling), or payment requested before goods are received
• Unknown vendors — invoices with no match in the vendor master, a common entry point for fraudulent billing
• Round-dollar invoices over $10,000 with no PO reference
• Credit notes unapplied for more than 30 days — money the business is owed but hasn't claimed
• Vendor balances exceeding an approved credit limit
• Payment terms breaches — invoices unpaid beyond agreed terms with no dispute on record
• Vendor concentration over 20% of total AP in a single vendor

Catching these consistently, every vendor and every period, is what turns AP review from a spreadsheet exercise into an actual control over cash.

What a completed AP review produces

A finished AP review isn't just an aging report — it's a documented workpaper a reviewer can sign off on and a CFO can act on for cash planning. A complete AP review package includes:

How OCTA Flow automates accounts payable review

OCTA Flow runs the mechanical parts of the review — the aging, the matching, the terms math — and leaves the judgment, and the sign-off, with your team. The workflow mirrors the process above:

1. Pick the Accounts Payable Review Skill. Flow already knows the full procedure: build the aging buckets, check payment terms compliance, scan for duplicate invoices and payments, run the three-way match, reconcile credit notes, and roll up the cash flow impact.
2. Connect your data. Point Flow at the accounting or ERP system, or upload the AP aging report — plus, if available, the vendor master, recent payment history, open purchase orders, goods receipts, and credit notes for deeper checks.
3. Run. Flow builds the aging schedule, tests every invoice against payment terms, scans for duplicates across invoices and payments, matches invoice to PO to goods receipt where that data exists, and calculates the cash flow forecast.
4. Review findings by severity. Instead of scrolling a full AP ledger, Flow surfaces only the exceptions — ranked by severity, each with a plain-English explanation and a recommended action: schedule the payment, recover a duplicate, request missing documentation, or escalate to a manager. Your team works the exceptions, not every line.
5. Sign off. Once exceptions are resolved and payments are approved, Flow assembles the workpaper with the full audit trail intact.

The result: the aging, matching, and terms-compliance math is done in a fraction of the time, and your people spend their hours on the handful of invoices that actually need a decision.

Control and trust: Flow proposes, you approve

This is what matters most to a firm putting its name on a client's cash position: OCTA Flow never writes to your books on its own. Every payment scheduled, credit applied, or correction made is a proposal that a person reviews and confirms before anything is posted. Flow does the aging, the matching, and the terms testing, and shows its reasoning; a person makes the call.

That control model runs through the whole review:

• Findings, not silent changes. Flow raises what it found and what it recommends — you decide.
• Severity and escalation built in. A duplicate payment or an unknown vendor is flagged as critical and routed to a manager rather than quietly buried in an aging report.
• A complete audit trail. Every match, proposed action, approval, and override is logged, so the review is fully traceable end to end.

You get the speed of automation with the accountability of human sign-off — exactly what a cash-critical ledger like accounts payable requires.

What the review draws on

To run an accounts payable review, Flow uses the same sources a preparer already works from:

• AP aging report — outstanding invoices by vendor and age bucket (required)
• Vendor master — payment terms, bank details, and contact information; enables payment-terms compliance checks and duplicate-vendor detection (optional)
• Payment history — recent payment transactions, typically the last 90 days; enables duplicate-payment detection (optional)
• Purchase orders — open POs, needed for the three-way match (optional)
• Goods receipt notes — confirms what was actually received, the other leg of the three-way match (optional)
• Credit notes — vendor credits received but not yet applied (optional)

Flow works from whatever your client has connected — it matches each input by its purpose, so it doesn't matter what the files are named or which system they came from. More optional inputs mean deeper checks; the aging report alone is enough to start.

Related skills and terms

Frequently Asked Questions

What is an accounts payable review? It's a periodic analysis of every outstanding vendor invoice by age and vendor, checking that payments are being made within agreed terms and screening for duplicate invoices, duplicate payments, and mismatches between invoices, purchase orders, and goods received.

How do you read an AP aging report? An AP aging report groups outstanding invoices into buckets by how long they've been unpaid — typically Current (0–30 days), 31–60 days, 61–90 days, and Over 90 days. A healthy ledger has most of its balance in the Current bucket; a growing balance in the 90+ bucket signals cash-flow strain, vendor-relationship risk, or invoices that were never actually reviewed.

What is a three-way match in accounts payable? It's the comparison of the vendor invoice against the purchase order and the goods receipt note before payment is approved. If all three agree on quantity and amount, the invoice is clean to pay. A mismatch — no PO, an invoice higher than the PO, or payment requested before goods arrive — is a red flag that should hold the payment until resolved.

How do you catch duplicate payments in accounts payable? Scan payment history for the same vendor paid the same amount within a short window (commonly 30 days), or an invoice number that's been referenced by more than one payment. Because the cash is already disbursed, duplicate payments should be treated as the most urgent finding in any AP review and routed for immediate recovery.

How often should accounts payable be reviewed? At minimum monthly, aligned with the close cycle. Businesses with high invoice volume or frequent vendor payments often review AP weekly so duplicate payments and overdue invoices are caught while they're still recoverable or correctable.

Can accounts payable review be automated? The aging, the duplicate-invoice and duplicate-payment scans, the three-way match, and the terms-compliance math can all be automated and reviewed, while decisions like disputing an invoice or approving an exception stay with your team. That's the model OCTA Flow uses.

Does OCTA Flow post payments or make corrections directly? No. Flow proposes every payment, credit application, and correction; a person on your team reviews and approves before anything is posted to the books. Nothing is written automatically.

See how firms run faster, fully-tested AP reviews with human sign-off → start a 30-day OCTA Flow trial.