Net 30 Calculator: Invoice Due Dates
Net 30 means full payment is due 30 calendar days after the invoice date, not 30 business days, and not 'end of next month'. Simple, except that a due date miscounted by a few days decides whether a late fee is chargeable and whether a payment is actually overdue. This calculator turns an invoice date and any net terms into the exact calendar due date and counts the days remaining, or overdue, from today.
- Due date (net 30)
- Sunday, September 20, 2026
- Days until due
- 30
If the due date lands on a weekend or holiday, the professional convention is to accept payment the next business day.
What to Know
- Net terms count calendar days from the invoice date, weekends and holidays included. Net 30 on an August 1 invoice is due August 31, whatever day of the week that is.
- Net 30 is the default US B2B term; construction and larger enterprise buyers commonly stretch to net 45, 60, or 90, and that stretch is a financing cost the seller carries.
- A late fee is only enforceable if it was stated before the work: on the invoice and ideally in the contract. The typical range is 1% to 1.5% per month.
- '2/10 net 30' offers 2% off for payment within 10 days; taken consistently, that discount is equivalent to a roughly 36% annualized return, which is why sharp buyers always take it.
- The federal Prompt Payment Act makes interest accrue automatically on government invoices unpaid after 30 days; most states mirror it for public work.
Late Fees and Payment Terms: What Is Typical
Conventions, not legal maximums. Several states cap late-fee interest through usury or prompt-payment statutes; check your state before charging above the typical range.
| Term | Typical practice | Notes |
|---|---|---|
| Net 30 | Payment due 30 days from invoice date | The default B2B term in the US; Net 15 and Net 60 are the common variants |
| Late fee | 1% to 1.5% per month (12% to 18% per year) | Must be stated on the invoice or in the contract before it can be charged |
| Grace period | 5 to 10 days is common courtesy | Not required by law; put it in writing if you offer one |
| Government work | 30 days, then interest accrues automatically | Federal Prompt Payment Act; most states have an equivalent for public contracts |
| Early-payment discount | 2/10 net 30 (2% off if paid in 10 days) | Worth stating explicitly as a line under the total |
Source: Federal Prompt Payment Act (31 USC 39); state prompt-payment and usury statutes · checked 2026-08
Frequently Asked Questions
Does net 30 mean business days?
No, calendar days. Thirty days after the invoice date, counting weekends and holidays. If the due date lands on a weekend, convention (not law) is to accept the next business day.
When does net 30 start: invoice date or delivery date?
From the invoice date, unless the contract says otherwise. Some buyers negotiate terms that run from receipt of invoice or receipt of goods; whichever applies should be printed on the invoice itself.
Can I charge a late fee the day after the due date?
Only if the fee was disclosed in advance, on the invoice or in the agreement. Many sellers add a short grace period of 5 to 10 days as goodwill, but nothing requires one.
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