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Short answer
Net 45 payment terms mean an invoice is due in full 45 days after the point the contract names as the start. Many explanations say “45 calendar days from the invoice date”, but that start point is a contract choice, not a fixed rule. A buyer who wants no argument later should have the purchase order, quote or credit agreement say what the 45 days count from.
What net 45 payment terms mean
Net 45 is a credit term: the seller ships or delivers first, and the buyer pays the invoiced amount within 45 days. “Net” means the full invoice amount, with no discount taken. One business-finance explainer from a payments vendor defines it as an invoice that must be paid in full within 45 calendar days of the invoice date (Ramp, checked 2026-11-03); treat that as a plain-language definition, not as authority for how a particular contract works.
A private net 45 term exists because the buyer and seller wrote it into their agreement. If you are comparing it with the shorter default, see the guide on when the 30 days start on a net 30 medical supply order and the comparison of net 30, net 60 and net 90 payment terms.
When the 45 days start: invoice, receipt or delivery
The part most explanations skip is the starting clock. The US federal Prompt Payment rules show clearly that “the date of the invoice”, “the date the invoice was received” and “a number of days after delivery” are three different clocks. Those rules bind federal agencies, not private buyers, but they are a useful public-sector reference point for what a precise term has to say.
| Possible starting clock | What the federal rule says | Source |
|---|---|---|
| Date of the invoice | For a prompt-payment discount, the specified time is determined from the date of the invoice, and the agency may pay the discounted amount only if payment is made within that time. | 31 U.S.C. 3904 |
| Date a proper invoice is received | The payment period begins on the date of receipt of a proper invoice. | 5 CFR 1315.4(f) |
| Seven days after delivery | An invoice is deemed received on the later of its actual receipt by the designated office or the seventh day after the property is actually delivered (or services are completed). An earlier acceptance, or a longer contract acceptance period, can substitute for the seventh day. | 5 CFR 1315.4(b)(1) |
The same rules also set the fallback: payment is due on the date specified in the contract, and if none is specified, 30 days after the start of the payment period (5 CFR 1315.4(g)(1); 31 U.S.C. 3903(a)(1)(B)). In other words, a contract-specified 45 days governs over the 30-day default, and it only exists if it is written down.
How net 45 works in a medical supply purchase
No medical-supply-specific law sets net 45. For lab, clinic and supply buyers it is the same commercial credit term as in any other trade: a seller extends 45 days of credit, and the buyer’s accounts-payable team schedules payment against the date the term says. Because dates drift between order, shipment, receipt of goods and receipt of the invoice, the practical question is always which of those dates the 45 days hang from. The questions below are an editorial checklist drawn from the federal clock distinctions above, not a legal requirement.
- Does the term say 45 days from the invoice date, from the date the invoice is received, or from delivery or acceptance?
- Does “45 days” mean calendar days? The agreement should say what happens when day 45 is not a business day.
- Is any early-payment discount tied to the same clock? A “2/10 net 45” style term has two dates, and the discount date is measured separately (see early payment discounts).
Which documents should carry the net 45 term
Because even the federal 30-day default applies only when no payment date is specified, a net 45 arrangement is only reliable when it appears in the documents that govern the order. A practical set to check for matching wording:
- Quote or price agreement: where the seller usually states the terms offered.
- Purchase order: the buyer’s order and its terms (see purchase order terms and conditions).
- Credit application or account agreement: where a buyer is approved for credit terms (see business credit applications).
- Invoice: should show the invoice date and the stated term so the due date can be calculated from the document itself.
- Delivery receipt or packing slip: matters if the term runs from delivery or acceptance, because it records that date.
If these documents disagree (for example a quote that says net 30 and an invoice that says net 45), the buyer and seller should settle which governs before the due date, not after a late fee is charged. See also late payment fees.
Common misunderstandings
“Net 45 always starts on the invoice date”
That is the common reading, but the federal rules show the start can legitimately be tied to receipt of a proper invoice or to delivery. Whichever is meant, the agreement should state it.
“Net 45 is the standard”
Not under the public-sector reference point: where a contract names no date, the federal default is 30 days. Longer terms are negotiated, and shorter alternatives such as due upon receipt also exist.
“The federal rules protect private buyers and sellers”
They do not. 31 U.S.C. 3903 and 5 CFR 1315.4 govern federal agency payments. A private net 45 term is purely a matter of contract.
FAQ
What is net 45 payment terms?
A credit term under which the full invoice amount is due 45 days after the start point the agreement defines, commonly the invoice date.
How does net 45 payment terms work in a medical supply purchase?
The seller delivers and invoices; the buyer pays within 45 days of the agreed start point. No medical-supply-specific rule changes this, so the term must be written into the order documents.
Which documents or terms go with net 45 payment terms?
The quote, purchase order, credit application or account agreement, invoice, and where relevant the delivery receipt, all stating the same term and the same starting clock.
What mistakes do small buyers make with net 45 payment terms?
Assuming the clock starts on the invoice date without checking, letting a quote, purchase order and invoice show different terms, and assuming day 45 moves when it falls on a weekend or holiday without that being written down.
Net 45 vs net 30: what changes?
Only the length of the credit period and, if you are relying on a default, whether anything is written down: where no date is specified, the federal default is 30 days. For the 30-day case in detail, read the net 30 guide.
This page is general information about payment terms, not legal or accounting advice.
Sources
- 31 U.S.C. 3903 (Prompt Payment Act), Cornell Legal Information Institute, https://www.law.cornell.edu/uscode/text/31/3903, checked 2026-11-03.
- 31 U.S.C. 3904, Cornell Legal Information Institute, https://www.law.cornell.edu/uscode/text/31/3904, checked 2026-11-03.
- 5 CFR 1315.4, Prompt payment, Cornell Legal Information Institute, https://www.law.cornell.edu/cfr/text/5/1315.4, checked 2026-11-03.
- Ramp, “Net 45 payment terms” (definition only), https://ramp.com/blog/net-45-payment-terms, checked 2026-11-03.
