FAR 52.232-1: Proper Invoices, Due Dates, and Late Payment Interest

FAR 52.232-1 is the standard payments clause in most federal fixed-price contracts. It commits the government to pay the prices set in the contract once you submit a proper invoice and the government accepts what you delivered, less any deductions the contract authorizes. The clause is short, but it works alongside the Prompt Payment clause at FAR 52.232-25 and the Prompt Payment Act at 31 U.S.C. Chapter 39, and those three together control when you actually get paid.

Which Contracts Use the Clause

Contracting officers must include FAR 52.232-1 in solicitations and contracts for fixed-price supply contracts, fixed-price service contracts, and contracts for nonregulated communication services.¹ Other arrangements get different payment clauses. Fixed-price construction uses FAR 52.232-5, time-and-materials uses FAR 52.232-7, and regulated communication services uses FAR 52.232-6. Cost-reimbursement work sits outside 52.232-1 entirely.

What the Clause Actually Says

The operative language commits the government to pay the contract prices “upon the submission of proper invoices or vouchers” for “supplies delivered and accepted or services rendered and accepted, less any deductions provided in this contract.”² Two conditions, both required. A proper invoice from you. Formal acceptance from the government. Until both are in place, the payment obligation hasn’t matured.

What Makes an Invoice “Proper”

Most avoidable payment delays start here. FAR 32.905 sets out what a proper invoice must contain, and missing a single required element gives the billing office grounds to return the invoice and reset your clock.³

A proper invoice includes:

Your business name and full address.
An invoice date (as close as possible to the day you transmit it) and a unique invoice number.
The contract or order number, including the specific line item being billed.
An itemized description of what you delivered or performed, with quantity, unit of measure, unit price, and extended price.
Shipment number, date of shipment, and any prompt payment discount terms.
The name and contact information for the person to notify if the invoice is defective.
Your Taxpayer Identification Number, if agency procedures require it on the invoice.
Electronic funds transfer banking information, on the invoice or already on file per the solicitation.
Any additional documentation the contract requires, such as proof of shipment or inspection certificates.

One trap worth flagging: even when TIN and EFT information aren’t required on the face of the invoice, correct EFT banking information must be on file with the government for the invoice to qualify as proper.³

If your invoice is defective, the designated billing office must return it within seven days of receipt with an explanation of what’s wrong.⁴ Shorter return windows apply to perishables: three days for meat and fish, five days for dairy and perishable agricultural commodities. If the billing office blows the return window, the payment due date gets adjusted for the delay when interest is calculated.³

Electronic Submission for DoD Contracts

Paper generally isn’t an option for Department of Defense work. DFARS 252.232-7003 requires contractors to submit payment requests and receiving reports electronically through Wide Area Workflow, which sits inside the Procurement Integrated Enterprise Environment.⁵ You can submit through electronic data interchange, secure file transfer, or direct input on the site. Limited exceptions exist for certain transportation payments, TRICARE health care services, and cases where the contracting officer approves an alternative in writing. When the government purchase card is the payment method, you still create a receiving report in WAWF even though no separate payment request is filed. Civilian agencies use their own portals; the specific system will be identified in your contract, and the same proper invoice elements apply.

Partial Payments on Accepted Deliveries

You don’t have to wait until final performance to get paid. Unless the contract says otherwise, the government will pay for partial deliveries it has accepted when either the amount due warrants payment, or you request payment and the amount due is at least $1,000 or 50 percent of the total contract price.² That second test is disjunctive. On a $1,500 contract, a $750 partial delivery qualifies on the 50 percent prong even though it’s under $1,000.

Deductions the Government Can Take

The clause pays “less any deductions provided in this contract.”² That authorizes reductions where the contract itself provides a basis, such as liquidated damages for late delivery, price reductions for nonconforming work, or credits for government-furnished property. The deduction has to trace to something the contract already authorizes.

When a contract contains two or more separate withholding provisions, the contracting officer typically also includes FAR 52.232-9, Limitation on Withholding of Payments, which caps the total that can be held back at any given time.¹ The ceiling itself will be stated in the clause, so check that language if your contract includes it.

When Payment Is Due and What Happens If It’s Late

Once a proper invoice is on file, the Prompt Payment clock under FAR 52.232-25 starts. The payment due date is the later of 30 days after the designated billing office receives your proper invoice, or 30 days after government acceptance.⁶ Acceptance usually happens on or before invoice processing, so the 30-day invoice clock is generally the binding deadline. If the billing office fails to annotate the invoice with the actual receipt date, the due date defaults to 30 days after the date on your invoice, provided no dispute exists over quantity, quality, or contract compliance.⁴

The government’s inspection window isn’t open-ended either. For interest calculation purposes, acceptance is deemed to occur on the seventh day after delivery of supplies or completion of services, unless there’s a disagreement over quantity, quality, or compliance, or the contract specifies a longer inspection period documented in the contract file.⁶ Actual acceptance before the seventh day controls if it happens earlier.

Miss the due date, and the Prompt Payment Act requires an automatic interest penalty. You don’t have to ask for it.⁴ Interest accrues from the day after the due date to the date payment is made.⁷ The rate is set by the Secretary of the Treasury and published in the Federal Register; for 2026, the Current Value of Funds Rate is 4 percent.⁸ Any penalty of $1.00 or more must be paid with the late payment, and unpaid interest compounds: any penalty still unpaid after 30 days is added to principal, and interest runs on the combined amount going forward. If the due date falls on a weekend or federal holiday, next-business-day payment doesn’t trigger a penalty.

There is one penalty you have to claim. If the government pays the principal late and fails to include the interest within 10 days, you can trigger an additional penalty by sending a written demand to the payment office, postmarked within 40 days of the date the invoice amount was paid.⁴ Miss the 40-day window and the additional penalty is forfeited. The amount is calculated under 5 CFR Part 1315 as a percentage of the late interest penalty.

Passing Accelerated Payments to Small Business Subcontractors

If your contract includes FAR 52.232-40 and you receive an accelerated payment from the government, you have 15 days to pass accelerated payments to your small business subcontractors to the maximum extent practicable, once you’ve received a proper invoice and any required documentation from them.⁹ You can’t charge a fee or require anything else in exchange for the faster payment, and the clause must be flowed down into all subcontracts with small business concerns, including those for commercial products and services.

1
Acquisition.GOV. 48 CFR 32.111 – Contract Clauses for Non-Commercial Purchases
2
Acquisition.GOV. 48 CFR 52.232-1 – Payments
3
Acquisition.GOV. 48 CFR 32.905 – Payment Documentation and Process
4
Acquisition.GOV. 48 CFR 52.232-25 – Prompt Payment
5
eCFR. 48 CFR 252.232-7003 – Electronic Submission of Payment Requests
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Acquisition.GOV. 48 CFR 32.904 – Determining Payment Due Dates
7
Office of the Law Revision Counsel. 31 USC 3902 – Interest Penalties
8
Treasury Financial Experience. Bulletin No. 2026-01
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Acquisition.GOV. 48 CFR 52.232-40 – Providing Accelerated Payments to Small Business Subcontractors