The Prompt Payment Act: Interest Rights Contractors Miss

Your accounts receivable report shows $487,000 outstanding from three federal contracts. The oldest invoice is 67 days past due. The contracting officer’s response to your third follow-up email: ‘It’s in the payment queue.’ Your line of credit charges 9.5% interest on the bridge financing keeping your payroll funded. The government owes you interest on those late payments. You have never claimed it.

Most small government contractors never file a Prompt Payment Act interest claim. Not because they were paid on time. Because nobody told them the right existed, or they assumed pursuing it would damage the relationship with their contracting officer. The money sits uncollected.

The Prompt Payment Act [31 USC 3901-3907] requires federal agencies to pay contractors within 30 days of receiving a proper invoice and to pay interest automatically when they miss that deadline. The Act applies to every federal contract, including fixed-price, cost-reimbursement, and time-and-materials. Interest accrues from the day after the payment due date until the government issues payment.

The rate resets every six months. It is the rate Treasury sets under 41 U.S.C. 7109 and publishes as the Prompt Payment interest rate, which is 4.75 percent for July 1 through December 31, 2026. The payment timelines, interest calculations, invoice requirements, and accounting entries below show contractors how to track and collect what they are owed.

How Long Does the Federal Government Have to Pay a Contractor Invoice?

Federal agencies must pay proper invoices within specific timeframes depending on the contract type. Under FAR 32.904(b)(1) the standard due date is the later of two events: the 30th day after the designated billing office receives a proper invoice, or the 30th day after the government accepts the supplies or services. Construction contracts receive a 14-day payment window for progress payments [FAR 52.232-27]; final payments on construction contracts follow the standard 30-day rule.

Meat, meat food products and fresh or frozen fish must be paid as close as possible to but not later than the 7th day after product delivery. Perishable agricultural commodities run to the 10th day after product delivery unless the contract says otherwise. Dairy products, edible fats and oils run to the 10th day after a proper invoice is received, which is a different trigger from the one that applies to produce [FAR 32.904(f)]. Architect-engineer contracts follow the standard 30-day rule [FAR 52.232-26].

The clock starts when the designated billing office receives a proper invoice, not when the contractor sends it. A proper invoice mailed Monday arrives Thursday. The 30-day clock starts Thursday. Electronic invoicing through WAWF (Wide Area Workflow) or IPP (Invoice Processing Platform) timestamps receipt automatically, eliminating delivery ambiguity.

Acceptance periods add time. When the contract specifies an acceptance period for delivered goods or services, the payment due date becomes 30 days after the later of (a) receipt of a proper invoice or (b) government acceptance of the deliverable. Under FAR 32.904(b), constructive acceptance occurs 7 days after delivery for supplies and services, unless the contract specifies otherwise or the contracting officer needs additional time for inspection. A contract with a 10-day acceptance period and a proper invoice received on delivery day gives the government up to 40 days from invoice receipt before interest accrues.

What Makes a Government Invoice ‘Proper’ Under FAR 32.905?

A proper invoice under FAR 32.905(b)(1) is one that includes every required element. There are ten of them, and two are conditional on agency procedures. A single missing element stops the payment clock and resets the 30-day timeline to zero.

The Prompt Payment Act clock starts only when the government receives a proper invoice. An improper invoice stops the clock entirely. The billing office must return it within 7 days of receipt, and faster on food contracts: 3 days for meat, meat food products and fish, 5 days for perishable agricultural commodities, dairy products and edible fats and oils. One missing element then costs the contractor a minimum 37-day delay.

But the rule cuts both ways, and this is the half that rarely gets invoked: under FAR 32.905(b)(3), if that notice is not timely, the billing office must adjust the due date for the purpose of determining an interest penalty. A government office that sits on your defective invoice for three weeks before rejecting it does not get those three weeks for free.

FAR 32.905(b)(1) lists them:

• the contractor’s name and address
• the invoice date and invoice number
• the contract number or other authorization, including order and line item number
• a description of the supplies or services with quantity, unit of measure, unit price and extended price
• shipping and payment terms
• the name and address of the contractor official to whom payment is to be sent
• the name, title, phone number and mailing address of the person to notify about a defective invoice
• the contractor’s Taxpayer Identification Number, if agency procedures require it on the invoice
• electronic funds transfer banking information, again only if agency procedures require it on the invoice
• anything else the contract calls for

One of those elements is commonly read backwards. The required name and address is the contractor official to whom payment is to be sent, meaning your own remit-to address, not the government’s designated payment office. Unit of measure gets dropped as often, and it is part of the required description.

Interim payments on cost-reimbursement service contracts work differently. FAR 32.905(b)(1) carves them out of the ten-element list, and 32.905(b)(2) makes such a request proper if it includes everything the contract requires. The contract is the checklist. In practice that means incurred costs broken down by cost element (labor, materials, subcontracts, other direct costs, indirect costs), supported by the contractor’s DCAA-compliant accounting system records. Missing cost breakdowns or unsupported indirect rate applications trigger invoice rejections on cost-type contracts.

Common Invoice Errors Killing the Payment Clock

Five invoice deficiencies account for the majority of proper invoice rejections and payment delays. Wrong contract number (a single transposed digit resets the clock). Missing CLIN references (the invoice total matches but CLIN-level detail is absent). Incorrect indirect rates applied (using an old provisional rate instead of the current approved rate). Missing receiving reports (the invoice arrives before the contracting officer’s representative signs the receiving report). Tax identification number mismatch between the invoice and System for Award Management registration.

Each rejection restarts the 30-day clock from the date the corrected invoice arrives. A contractor who submits three invoices with errors before getting it right waits 90+ days without interest protection on any of them. The chart of accounts setup should include a receivables aging report flagging invoices approaching 30 days without payment.

Calculating Prompt Payment Act Interest

31 USC 3902(a) sets the rate by reference: interest is computed at the rate the Secretary of the Treasury establishes and publishes in the Federal Register for interest payments under 41 U.S.C. 7109, in effect when the agency accrues the obligation. Treasury publishes it as the Prompt Payment interest rate, and it resets every January and July. For July 1 through December 31, 2026 it is 4.75 percent [Treasury Prompt Payment interest rate page]. Verify the rate for your period before submitting a claim.

Do not use the Current Value of Funds Rate for this. It is a different Treasury rate, published for federal debt collection, cash discounts and rebate evaluation, and it is set annually rather than semiannually. For 2026 it is 4.00 percent. The two rates sit close enough together that substituting one for the other produces a number that looks plausible and is still wrong.

Interest accrues from the day after the payment due date through the payment date. Two limits apply that catch contractors out. Under 5 CFR 1315.10(a)(5), Prompt Payment interest stops accruing after one year, and it also stops once a claim for those penalties is filed under the Contract Disputes Act. An invoice that went unpaid for three years does not carry three years of interest.

One note on the interest mechanics: 31 USC 3902(e) provides that any unpaid interest penalty remaining after 30 days is added to the principal, and interest accrues on that combined amount from then on. In practice, most PPA interest claims are resolved before this additional-penalty mechanism triggers, but contractors should be aware it exists.

The formula: Invoice Amount x (Interest Rate / 360) x Number of Days Late. The 360-day year is not a rounding choice. 5 CFR 1315.10(a)(9) requires it. A $100,000 invoice paid 45 days late at the current 4.75 percent: $100,000 x (0.0475 / 360) x 45 = $593.75. Small amounts on individual invoices. Significant amounts across a year’s worth of delayed payments on multiple contracts.

The additional penalty under FAR 32.907 requires the government to pay an extra penalty amount when: (1) the government owes $1 or more in interest, (2) the payment office fails to pay that interest within 10 days after paying the invoice, and (3) the contractor submits a written demand within 40 days of invoice payment.

The automatic interest obligation itself derives from 31 USC 3902, which requires agencies to pay interest without the contractor having to request it. In practice, many payment offices do not self-identify late payments. Contractors should track invoice due dates against payment receipt dates and submit interest calculations to the payment office when payments arrive late. Contractors who do not track payment dates against invoice dates forfeit the interest by default.

Two more things decide whether a claim succeeds. First, FAR 32.907(d) blocks interest where the delay came from a disagreement over the payment amount, contract compliance, or amounts properly withheld or retained. That is the most common reason a claim goes nowhere, and it is worth checking before you file.

Second, FAR 32.907(c)(2) fixes what a written demand for the additional penalty must contain: assert specifically that late payment interest is due under a named invoice and request all overdue interest plus the additional penalty, attach a copy of that invoice, and state that the principal has been received and on what date. The rule also says the government must not request additional data, so a demand carrying those three things is complete.

Prompt Payment Act Rights for Subcontractors

Prime contractors on construction contracts are required by FAR 52.232-27(c)(1) to pay subcontractors for satisfactory performance within 7 days of receiving payment from the government. If the prime pays late, the subcontractor is owed interest at the same Treasury rate.

On non-construction federal contracts, the prime-to-subcontractor payment obligation arises from flow-down clauses in the prime contract rather than from FAR 52.232-25 directly. FAR 52.232-25 governs government-to-prime-contractor payments only. Subcontractors should review their subcontract agreement and the applicable flow-down provisions for the specific payment timing that applies to their situation.

This creates a two-tier structure on construction contracts. The government pays the prime within 14 days (or owes interest). The prime pays the subcontractor within 7 days of receiving government payment (or owes interest). Subcontractors should track two dates: when the prime received government payment (request this information from the prime) and when the subcontractor received payment from the prime. Many primes exceed the 7-day window. The interest obligation is real, though subcontractors rarely pursue it for relationship reasons.

Accounting for Prompt Payment Act Interest

Record interest receivable when a payment exceeds its due date. The journal entry: debit Interest Receivable (current asset), credit Interest Income (other revenue). When the interest payment arrives, debit Cash, credit Interest Receivable. Code interest income to a dedicated account separate from contract revenue. Prompt Payment Act interest is not contract revenue and does not flow through indirect rate calculations.

Track every invoice with three dates: date submitted, date the government received it (WAWF confirmation), and date payment was received. The gap between the 30-day due date and actual payment date drives the interest calculation. A spreadsheet or QuickBooks memorized report comparing received date plus 30 to payment date flags every late payment automatically.

Cash flow impact on small contractors is the real cost of late government payments. As an example: a firm with $2 million in annual federal billings and an average payment delay of 15 days beyond the 30-day window carries roughly $82,000 of additional receivables at any given time, on top of the balance the normal 30-day cycle already ties up. At a 9% line of credit rate, the carrying cost on that balance reaches roughly $7,400 annually. Actual impact depends on invoice timing and payment patterns across the contractor’s portfolio. The Prompt Payment Act interest recovers part of that carrying cost.

Why Contractors Leave Interest Money Unclaimed

Three patterns explain why most small contractors never collect Prompt Payment Act interest they are owed. Understanding these patterns matters because the money is often substantial in aggregate.

1. Relationship protection. Contractors fear that claiming interest will antagonize the contracting officer and harm future contract opportunities. Claiming interest is a statutory entitlement under the contract, not a discretionary favor, but the perception persists. Claiming a statutory right does not create an adversarial relationship, but not claiming it creates a pattern the government has no incentive to correct.
2. Tracking gaps. Without a system comparing invoice receipt dates to payment dates, contractors never identify which payments were late. The payment arrives, accounting records it, and nobody checks whether it arrived within 30 days. By the time someone reviews, the documentation window has passed.
3. Small individual amounts. Interest on a single late payment might total $200. Contractors dismiss it. Across 50 invoices per year with an average 10-day delay, that dismissal costs $10,000 annually. The aggregate matters.

Build interest tracking into the standard invoicing workflow. When the payment posts to the bank, compare the deposit date against the invoice due date. If the payment crossed the 30-day line, calculate the interest and submit the claim. Processing time is about 15 minutes per claim. What a contractor recovers depends entirely on how often and how badly its agencies pay late, so the only way to know your own number is to run the comparison for a year of invoices.

Frequently Asked Questions

Key Takeaways

• The Prompt Payment Act requires agencies to pay proper invoices within 30 days (14 days for construction progress payments) and pay interest automatically when they miss that deadline [31 USC 3902]. The interest rate is the one Treasury sets under 41 U.S.C. 7109 and publishes semiannually as the Prompt Payment interest rate, 4.75 percent for the second half of 2026. It is not the Current Value of Funds Rate. Most small contractors never claim the interest they are owed, and interest stops accruing after one year, so the delay itself costs money.
• A proper invoice under FAR 32.905(b)(1) requires ten elements, two of which apply only if agency procedures call for them. One missing element resets the 30-day clock entirely, and if the government misses its own 7-day deadline to reject the invoice, the due date is adjusted back in your favor. The five most common deficiencies: wrong contract number, missing CLIN detail, incorrect indirect rates, absent receiving reports, and TIN mismatches. Fix invoice templates once. Prevent recurring rejections permanently.
• On construction contracts, subcontractors receive a 7-day payment window after the prime receives government payment [FAR 52.232-27(c)(1)]. On other contract types, review the flow-down provisions in your subcontract for the applicable payment timing. Track both the government-to-prime payment date and the prime-to-sub payment date.
• Record interest receivable the day a payment crosses the due date. Code Prompt Payment Act interest to an other-income account, not contract revenue. The interest does not affect indirect rate calculations or the incurred cost submission.

Late government payments are a cost of doing federal business. The Prompt Payment Act shifts part of that cost back to the government through mandatory interest. The contractors who track it collect it. The contractors who ignore it subsidize the agency’s slow payment process with their own working capital. Run the Compliance Readiness Check to evaluate whether your invoicing process captures all required elements. Billing the government and not tracking payment timing? Book a discovery call with our CPA-managed team.