Invoice Due Date Calculator
"Net 30" is a promise. This turns it into a date, the one you chase, and the one you tell your client.
Most vendor contracts count calendar days from the invoice date, then roll a weekend/holiday due date forward. Late-fee math: daily rate = amount × % ÷ 365 on the "days late" row.
How the math works
- Net N = invoice (or delivery) date + N calendar days. Day 0 is the invoice date, so Net 30 issued Jan 1 is due Jan 31.
- EOM = last calendar day of the invoice month; EOM+15/+30 add days after that, then roll if needed.
- Rollover skips Saturdays, Sundays, and US federal holidays (observed: Sat holidays move to Friday, Sunday to Monday).
- Business days remaining counts Mon–Fri minus holidays between today and the due date, the real working window for collections.
- Late fee = amount × 1.5% ÷ 30 × 15 (1.5%/month is the standard contract rate).
Federal holiday set: New Year's Day, MLK Day, Presidents Day, Memorial Day, Juneteenth, Independence Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving, Christmas, computed by the official rules for the due-date year.
Is Net 30 30 days from the invoice date or the delivery date?
Usually the invoice date, unless the contract says "from completion" or "from receipt." Government invoices often count from receipt of a proper invoice. Pick the basis row to match your paperwork.
What if the due date lands on a weekend?
Contracts vary: many roll to the next business day, some roll back, some ignore it. The rollover selector shows all three so you can quote the date your contract produces.
What is EOM 30?
End of month + 30: an invoice dated Mar 10 is due Mar 31 (EOM), plus 30 days = Apr 30. It stretches cash flow the most of the common term sets.