A supplier invoice is a claim, not a fact. Approving it only confirms that someone expected a bill from that vendor; whether the charges are right is a separate question, and answering it is the job of an invoice audit.
An invoice audit is the line-by-line test of a supplier invoice against the contract, the agreed rates and evidence that the goods or services were delivered, run before payment to stop errors or after payment to recover them. The method holds across accounts payable (AP), but the reference data changes: a purchase order and receiving record for goods, a rate schedule and service inventory for telecom, a tariff and meter read for utilities. Recurring telecom and utility invoices arrive with no purchase order, which is why they need a category-specific audit.
Skipping the test has a measurable cost. In the Association of Certified Fraud Examiners (ACFE) report Occupational Fraud 2026, the fraud examiners surveyed estimate that organizations lose 5% of revenue to fraud each year, and the typical scheme among the study’s 2,402 cases ran 12 months before anyone caught it. RadiusPoint, founded in 1992, audits telecom and utility invoices through its ExpenseLogic platform; for a Fortune 100 manufacturer, that work produced $450,000 in telecom refunds in the first year.
Key takeaways
- An invoice audit tests each charge against the contract, the agreed rate and proof of delivery.
- Federal law (31 U.S.C. § 3351) defines improper payments to include duplicates, payments for things not received and missed discounts, giving AP teams a ready-made test list.
- Pre-payment audits prevent losses; post-payment audits recover them, but only inside claim windows, which run two years for tariffed telecom overcharges (47 U.S.C. § 415).
- Telecom and utility invoices have no purchase order, so they’re tested against inventories, contract rates, tariffs and meter data.
- The ACFE’s 2026 study names billing schemes among the most serious fraud risks when frequency and financial damage are weighed together.
The short version: check every supplier invoice before payment, and audit every line of recurring telecom and utility spend against contract rates and an inventory of live services, because those errors repeat each month until someone disputes them.
What does an invoice audit actually test?
An invoice audit tests whether each charge was owed, priced at the contract rate, actually delivered, not paid twice, and net of discounts due. Those tests aren’t arbitrary. They mirror how US federal law defines an improper payment in the Payment Integrity Information Act of 2019, which lists payments to ineligible recipients, duplicate payments, payments for goods or services not received, and payments that ignore applicable discounts.
| Improper payment type (31 U.S.C. § 3351) | What the audit compares | General AP example | Telecom or utility example |
|---|---|---|---|
| Incorrect amount, including an overpayment | Billed price against the contract or rate schedule | Unit price above the agreed price list | Circuit billed above its contracted rate |
| Duplicate payment | Invoice number, amount and period against payment history | Same invoice under two vendor records | Same period billed on an old and a new account |
| Good or service not received | Billed items against receiving records or the service inventory | Goods that never reached the dock | Line still billing at a closed location |
| Ineligible good or service | Billed items against what the contract allows | Excluded item invoiced anyway | Feature or plan nobody ordered |
| Missed applicable discount | Contract terms against the invoice net | Volume discount left off | Contracted credit missing |
| Ineligible recipient | Payee details against the vendor master | Bank details changed by email request | Bill from a provider absent from the inventory |
The last row is where fraud gets in. In the Association for Financial Professionals (AFP) 2026 Payments Fraud and Control Survey of 465 treasury practitioners, 76% of US organizations reported attempted or actual payments fraud in 2025, and business email compromise affected 74%.
Approval and matching test something else: an approver confirms the spend was authorized, and a three-way match confirms the invoice agrees with a purchase order and receiving record. Neither asks whether a recurring charge is still at the contracted rate or whether the service still exists, the gap explained in how an invoice audit differs from three-way matching.
Pre-payment audits prevent losses; post-payment audits recover them
A pre-payment audit stops a wrong charge before cash leaves, while a post-payment recovery audit reclaims money already paid, within whatever claim window remains. US federal law builds both into its payment rules. The Payment Integrity Information Act calls for both prepayment and postpayment controls and requires recovery audits for any agency program spending $1,000,000 or more a year when auditing is cost-effective.
| Dimension | Pre-payment audit | Post-payment recovery audit |
|---|---|---|
| When it runs | Between invoice receipt and approval | After payment, often months or years later |
| What it needs | Current rates, purchase orders or a service inventory, the vendor master | Paid invoice history, contract terms in force at the time, proof of delivery |
| Hard limit | Only as good as the reference data on the day | Claim windows: two years for tariffed telecom overcharges (47 U.S.C. § 415); four years by default for sale-of-goods contracts, reducible to one year by agreement (UCC § 2-725) |
Payment errors mostly cost the payer: the Government Accountability Office (GAO) found overpayments made up $153 billion of an estimated $186 billion in federal improper payments in fiscal year 2025, about 82%. Recovery also runs on a clock. For tariffed telecom charges, a written claim to the carrier inside the two-year window extends it, so file disputes in writing as soon as an error is confirmed.
How does the invoice audit process work, step by step?
The invoice audit process gathers reference documents, captures every line, tests each charge, verifies the vendor, disputes errors, and records the cause so it stops. The order matters. Testing before the reference set is complete produces false passes, because a charge can only fail against a rate, a record, or an inventory you’ve actually loaded.
- Assemble the reference set: contracts, rate schedules, purchase orders and receiving records where they exist, the vendor master, and an inventory of live services and locations for recurring spend.
- Capture every line item, not a sample.
- Test each charge for price, quantity or service existence, duplicates across accounts and periods, taxes and surcharges, and promised credits.
- Verify the payee and any change to remittance details through a contact already on file, never through the message requesting the change.
- Dispute in writing and track to credit. A finding isn’t recovered until the credit appears on a later invoice or the refund arrives.
- Record the finding and fix the cause: log the charge, the reference it failed and the amount, then correct the contract record, inventory or approval rule that let it through.
The invoice auditing process is the same for every spend category; only step one’s reference set changes. Step six matters more than it looks. Under the Payment Integrity Information Act, a federal payment that can’t be shown proper for lack of documentation is treated as improper for estimation purposes, and that’s a sound rule for any audit trail.
Why do telecom and utility invoices need their own audit?
Telecom and utility invoices bill recurring services without purchase orders, so they must be audited against contracts, service inventories, tariffs and meter data instead. A general AP review sees a familiar vendor, a familiar amount and an approved account, then passes a charge that may have stopped being valid months earlier.
Telecom invoices also carry regulatory rules a generic audit doesn’t know. Under Federal Communications Commission (FCC) rule 47 CFR § 54.712, a carrier’s Universal Service Fund line item can’t exceed the interstate portion of the bill times the quarter’s contribution factor, which is 42.0% for the fourth quarter of 2026. No purchase order tells you which charges are interstate. The wider scope is covered in what a line-item telecom audit finds.
Utility bills fail differently. The reference is a tariff or supply contract plus the meter, and the core test is consumption. US Energy Information Administration (EIA) data show 16.5 million of the 20.4 million commercial-sector electric meters in 2024 were advanced meters, about 81%, which EIA defines as recording usage at least hourly, so a closed store still drawing daytime load shows up. The checks for a single bill are in how to audit a utility bill for errors.
How RadiusPoint and ExpenseLogic audit every telecom and utility line
RadiusPoint audits every line of client telecom and utility invoices in ExpenseLogic against contracted rates, tariffs and inventory, without sampling. The platform is software; the audit is software plus people. RadiusPoint staff work the exceptions, chase the carriers, file the disputes and close the tickets.
Within RadiusPoint’s telecom expense management (TEM) and Utility Expense Management (UEM) services, each ExpenseLogic capability answers a specific failure:
- Line-item audit across wireline, wireless and data circuits against contracted rates and inventory, so a mismatched charge is flagged, not approved.
- Daily missing-bill reporting, because an invoice that never arrives can’t be audited and can turn into late fees.
- Closed-location billing exception reports for service still billing at shut sites. One multi-location client recovered $1,500 a month, $18,000 a year, from utilities at closed locations.
- Meter-level utility audit of contract and tariff rates, consumption and thresholds, so a misapplied rate surfaces at the meter, not inside an account total.
- Accrual and general ledger (GL) interface files with enterprise resource planning (ERP) integration, so corrected amounts reach the general ledger without rekeying.
Published RadiusPoint client results include $120,000 a year from contract rate optimization, $18,000 a year from eliminating unneeded toll-free numbers, and $174,000 in re-credits recovered through inventory management.
Sharon Watkins worked in internal audit at a bank before founding RadiusPoint in 1992. RadiusPoint was named a Distinguished Vendor in the Amalgam Insights 2024 Telecom Expense Management Vendor SmartList, and ExpenseLogic holds a 4.8 rating from 31 Capterra reviews. As Watkins has put it: “The telecom industry can’t keep up with the ubiquitous challenges and doesn’t have the time to identify savings.”
Where invoice audits miss money they should have caught
Invoice audits miss money when they sample instead of testing every line, start after claim windows close, or lack an inventory to test against. Control gaps compound all three. In the ACFE’s 2026 study, more than half of fraud cases involved either missing internal controls or an override of controls that existed.
Sampling estimates an error rate; it doesn’t recover dollars in lines nobody opened. Delay is the second leak: the ACFE found schemes caught within six months had a median loss of $40,000, against more than $1.1 million for schemes running past five years, and recurring billing errors compound the same way.
Without an inventory of record, an audit can’t tell you a correctly priced service should have been disconnected. A credit recovered without fixing the contract record or inventory returns next month. The ACFE tied proactive data monitoring, management review and surprise audits to lower losses and faster detection, and a standing line-item audit is proactive data monitoring.
What should you do before the next invoice cycle closes?
Before the next cycle closes, pick one recurring vendor category, build its inventory of live services, and audit one month of invoices line by line. A single month of line-level results shows whether the errors are isolated or structural, and structural errors repeat on every invoice until someone disputes them.
Every month that goes unaudited is another month of the same errors billing at the same rate. If you’re scoping a broader program, what invoice auditing services cover and cost sets out the options.
Frequently asked questions
Is invoice auditing the same as invoice reconciliation?
No. Reconciliation confirms that what you paid matches what you recorded in the ledger and on the bank statement. Invoice auditing asks whether the charge should have been billed at all, at that price, for that period. A fully reconciled ledger can still hold an overcharge that was paid and recorded correctly.
Can a small business run its own invoice audit?
Yes. The ACFE’s 2026 report found smaller businesses had the highest median fraud losses of any organization size. A small team can start with its largest recurring vendors: pull each contract, list what’s actually in service, and test one month of invoices against both before widening the scope.
Who should perform an invoice audit, your AP team or an outside firm?
Either can, provided the auditor isn’t the person who approved the spend. Federal recovery audit rules let agencies use their own staff, other agencies or private contractors, while the agency keeps the final decision on any overpayment claim. The same split works anywhere: the auditor finds and documents, and your organization decides what to dispute.
Can an invoice audit catch fraud, or only billing mistakes?
Both, though it’s built around errors. The tests that flag an overcharge also surface services never received, duplicates and payees that don’t match the vendor master, which is how billing schemes work. The ACFE lists an unusually close relationship with a vendor or customer among the behavioral red flags with the highest median losses, $300,000 per case.
References
- Association of Certified Fraud Examiners, Occupational Fraud 2026: A Report to the Nations, 2026. acfe.com
- Association of Certified Fraud Examiners, “Report: 84% of fraudsters show at least one behavioral red flag,” press release, May 12, 2026. acfe.com
- Association of Certified Fraud Examiners, “Key Findings from Occupational Fraud 2026: A Report to the Nations,” ACFE Insights, May 19, 2026. acfe.com
- Association for Financial Professionals, “Over 75 Percent of US Firms Experienced Payments Fraud in 2025 While AI Adoption for Fraud Mitigation Lags,” press release, April 14, 2026. financialprofessionals.org
- US Congress, Payment Integrity Information Act of 2019, Public Law 116-117, 134 Stat. 113 (2020), 31 U.S.C. §§ 3351 and 3352. govinfo.gov
- US Government Accountability Office, “Payment Integrity: Agencies’ Estimated Improper Payments Increased to $186 Billion in Fiscal Year 2025,” GAO-26-108694, 2026. gao.gov
- US Government Accountability Office, “GAO Reports Improper Payments Rose to an Estimated $186 billion Across the Federal Government in Fiscal Year 2025,” press release, April 27, 2026. gao.gov
- 47 U.S.C. § 415, Limitations of actions. law.cornell.edu
- 47 CFR § 54.712, Contributor recovery of universal service costs from end users. law.cornell.edu
- Federal Communications Commission, Office of Managing Director, “Proposed Fourth Quarter 2026 Universal Service Contribution Factor,” Public Notice DA 26-946, September 2026. docs.fcc.gov
- Uniform Commercial Code § 2-725, Statute of Limitations in Contracts for Sale. law.cornell.edu
- US Energy Information Administration, Electric Power Annual, Table 10.05, Advanced Metering Count by Technology Type, 2015 through 2024. eia.gov
- US Energy Information Administration, “How many smart meters are installed in the United States, and who has them?” eia.gov
- Amalgam Insights, 2024 Vendor SmartList for Telecom Expense Management, Distinguished Vendor designation, February 2024.
- Capterra, ExpenseLogic reviews, 4.8 from 31 reviews. capterra.com
- RadiusPoint, published client case studies: Fortune 100 manufacturer telecom refunds; contract rate optimization; toll-free number elimination; inventory re-credits; closed-location utility recovery.
Third-party figures describe the populations each source studied and won’t predict results for a specific organization. RadiusPoint client results reflect individual engagements, and outcomes depend on invoice volume, contract terms, inventory accuracy and how quickly errors are disputed. This article is general information, not legal or accounting advice.