To approve an invoice for payment, verify the vendor’s bill against your purchase order and proof of receipt, route it to someone with the right spending authority, confirm the tax treatment is correct, and archive the full packet before the payment is cut. That sequence is what separates a controlled disbursement from an overpayment, a duplicate check, or a fraudulent transfer. Each step exists because skipping it is where money goes missing.
Gather the Documents You Need Before Approving Anything
An approver should never look at an invoice in isolation. Before the file lands on anyone’s desk for sign-off, accounts payable needs to assemble the underlying paper trail.
Start with the invoice itself. It should carry the vendor’s name, a unique invoice number, service or delivery dates, line-item descriptions, quantities, unit prices, and the total due. If any of those are missing, the invoice goes back to the vendor rather than forward for approval.
Pull the original purchase order your company issued when it placed the order. That document is the benchmark everything else is measured against. If physical goods were involved, add the receiving report or packing slip from the warehouse confirming what actually arrived. For services, the equivalent is a signed completion certificate or timesheet from the department that requested the work.
Tax documentation belongs in the file too. Collect a completed Form W-9 from every domestic vendor before processing their first payment; foreign vendors provide the appropriate Form W-8 instead.1Internal Revenue Service. Instructions for the Requester of Form W-9 Without a valid taxpayer identification number on file, you may be required to withhold a percentage of each payment under backup withholding rules. For 2026, you must file a Form 1099-NEC for any unincorporated vendor you pay $2,000 or more in nonemployee compensation during the year.2IRS.gov. 2026 General Instructions for Certain Information Returns
Now scan the invoice for math errors, missing line items, and unit prices that don’t match the original quote. Common problems include shipping charges the vendor added after the fact and taxes applied to items your organization considers exempt. Any inconsistency stops the process until the vendor issues a corrected invoice or credit memo. This is also where you catch duplicates, which show up more often than most people expect when vendors resend bills with slightly different dates or reformatted invoice numbers.
Match the Invoice Against the Purchase Order and Receipt
With the documents assembled, the core verification step is matching them against each other. What was ordered, what was received, and what was billed all need to agree within an acceptable tolerance. There are three common levels of rigor.
Two-Way Matching
The simplest version compares just the purchase order and the invoice. If the prices and quantities line up with what the purchase order authorized, the match passes. Two-way matching is appropriate for low-risk, routine purchases where delivery confirmation isn’t a concern, such as recurring software subscriptions or utility bills.
Three-Way Matching
Three-way matching adds the receiving report as a third checkpoint. The quantity on the purchase order must match the quantity the warehouse confirmed receiving, which must match the quantity the vendor billed. The unit price on the invoice must also mirror the price on the original purchase order. Most companies set tolerance thresholds so minor rounding differences don’t stall approvals, but variances beyond a few dollars or a small percentage trigger a manual review.
This is where most invoice problems surface. If the receiving report shows a partial shipment or damaged goods, the invoice cannot be approved for the full amount. The buyer contacts the vendor, and the vendor issues a credit memo or replacement before the adjusted amount moves forward. Three-way matching is the standard for any organization buying physical goods in meaningful quantities.
Four-Way Matching
Four-way matching adds an inspection or acceptance step on top of the three-way check. Beyond confirming that goods arrived, someone with quality authority must sign off that the goods meet the required specifications. The quantity billed cannot exceed the quantity formally accepted, not just the quantity received.3Oracle Payables Help. Two-, Three-, and Four-way Matching This level of scrutiny is common where defective materials create serious downstream costs.
Route the Invoice to Someone With Spending Authority
After the numbers check out, a human with the right level of authority has to approve payment. Which human depends on the dollar amount. Organizations set thresholds that route invoices to progressively senior people: a team lead might approve invoices up to $1,000, a department manager up to $10,000, and a vice president or CFO for anything above that. The exact numbers vary, but the principle is universal: bigger dollars get more senior eyes.
These hierarchies prevent any single employee from controlling the full payment cycle. A maintenance supervisor who can authorize small repairs should not also have the power to sign off on a six-figure capital expenditure. When someone approves an invoice, they are certifying that the expense is legitimate, within budget, and properly documented.
Segregation of duties matters as much as the dollar thresholds. The person who processes vendor invoices should not be the same person who sets up new vendors in the master file, authorizes payments, signs checks, or reconciles the bank account. When one employee controls multiple steps, the door opens to fictitious vendor schemes.
Digital approvals are legally valid and increasingly the norm. Under the E-SIGN Act, an electronic signature carries the same legal weight as ink on paper, provided the signer intended to sign and the signature is attached to or logically associated with the record.4Office of the Law Revision Counsel. 15 USC Ch 96 – Electronic Signatures in Global and National Commerce Act Most AP automation platforms satisfy the requirement through login-authenticated approval clicks and timestamped audit trails. If your company still routes paper for wet signatures, the bottleneck is organizational habit rather than legal necessity.
Watch for Fraud and Duplicate Payments
Invoice approval is one of the highest-risk touchpoints in a business, and the schemes are more sophisticated than most finance teams expect. Business email compromise is a serious threat: a scammer impersonates a known vendor and sends an invoice with updated bank routing information, or infiltrates a company’s email system and inserts themselves into a legitimate billing thread.5Federal Bureau of Investigation. Business Email Compromise The invoice looks real because it is based on real transaction data. The FBI recommends verifying any change in payment instructions by calling the vendor at a previously known phone number rather than one listed in the suspicious email.
Duplicate payments are a quieter problem that drains just as much cash. They happen when a vendor resends an invoice with a slightly different number or date, or when a clerk makes a typo on the invoice number so the system treats it as a new entry. Automated matching tools that use fuzzy logic to flag invoices with similar numbers, amounts, and vendor names catch far more duplicates than exact-match filters. If your AP software only flags exact duplicates, it is missing the most common scenarios.
Fabricating invoices to funnel company funds can trigger federal wire fraud charges when the scheme involves electronic communications. Wire fraud carries a prison term of up to 20 years, or up to 30 years if the fraud affects a financial institution.6Office of the Law Revision Counsel. 18 USC 1343 – Fraud by Wire, Radio, or Television For government entities and their contractors, a separate statute covering theft of public funds carries penalties of up to ten years.7Office of the Law Revision Counsel. 18 USC 641 – Public Money, Property or Records
Confirm the Tax Treatment Before You Pay
Accounts payable is often the first line of defense on sales and use tax compliance, and this catches many companies off guard. When a vendor charges sales tax on an invoice, verify that the rate matches your location’s combined state and local rate and that the items are actually taxable. Overpaying sales tax on exempt purchases is money you have to claw back later through refund claims.
The trickier situation is when a vendor does not charge sales tax at all. If you purchased taxable goods or services from an out-of-state vendor who is not registered to collect tax in your state, your company likely owes use tax on that purchase. Use tax is essentially sales tax that the buyer self-assesses and remits when the seller did not collect it. Failing to accrue use tax is one of the most common findings in state tax audits, and the liability compounds quickly across hundreds of invoices. Someone in the AP process needs to flag taxable invoices that arrive without tax charges and route them for accrual.
Time the Payment for Discounts and Avoid Late Interest
The timing of your payment directly affects what you actually owe. Many vendors offer early payment discounts, commonly structured as “2/10 net 30,” meaning you get a 2% discount for paying within 10 days instead of the standard 30.8J.P. Morgan. How Net Payment Terms Affect Working Capital On a $50,000 invoice, that is $1,000 saved for paying 20 days early. Over a year of vendor bills, the savings add up, but only if the AP team processes approvals fast enough to hit the window. A slow approval chain that takes 15 days to route an invoice through three signers kills the discount before anyone notices.
Late payments run the other direction. For federal government agencies paying contractors, the Prompt Payment Act sets the interest rate at 4.125% per year for the first half of 2026, running from the day after the due date until the payment clears.9Federal Register. Prompt Payment Interest Rate; Contract Disputes Act Private commercial contracts set their own late payment terms, which vary widely. Contractual interest rates in the 8% to 15% annual range are generally considered enforceable, though state usury laws cap the maximum and those caps differ by jurisdiction.
Record the Payment and Archive the File
Once all approvals are secured, the AP specialist enters the invoice into the accounting system, recording the liability on the balance sheet. The entry codes the expense to the correct general ledger account and cost center, then queues the payment for the next check run or electronic transfer based on the agreed credit terms.
Every piece of supporting documentation needs to be archived together: the original invoice, the purchase order, the receiving report, the matching results, and the approval record with timestamps or signatures. That packet is what auditors will pull when they test your AP controls, and it is what the IRS expects to see if it examines your expense deductions.
The IRS generally requires records supporting income, deductions, and credits to be kept for at least three years from the filing date. If you underreport income by more than 25%, the retention period extends to six years. If you file a claim for a loss from worthless securities or bad debt, keep records for seven years. If you never file a return, the retention clock never starts, so those records must be kept indefinitely.10Internal Revenue Service. How Long Should I Keep Records Employment tax records require a minimum of four years. Most companies default to a seven-year retention policy for all AP records to cover the longest common scenario without sorting documents into different buckets.