How due dates are counted
Add the days in the term to the invoice date, which counts as day zero. End-of-month terms start the count somewhere else, and that can move the due date into another month.
How a due date is worked out
The invoice date is day zero, and the count starts the day after. Add the days in the terms to the invoice date. For example, Net 30 on an invoice dated 1 August is due on 31 August. Net terms mean calendar days unless your agreement says otherwise, so weekends and public holidays are counted.
| Due on receipt | Payable when the invoice arrives, so the due date is the invoice date |
|---|---|
| Net 7 to Net 90 | That many days after the invoice date |
| End of the invoice month | The last day of the month the invoice is dated in |
| Net 30 from end of month | 30 days after the last day of the invoice month |
The count, step by step:
- Start from the invoice date. It is day zero; the count begins the day after.
- On end-of-month terms, move the start to the last day of the month the invoice is dated in.
- Add the days in the term: calendar days, unless your agreement says working days.
- If the result lands on a weekend, it stays there unless your agreement moves it; see below.
End of month is a different starting line, not a longer term
EOM (end of month) terms count from the last day of the invoice month. The term is common in Europe and across much of Asia. Say you date an invoice 2 January on Net 30 EOM. It isn't due on 1 February: the count starts on 31 January, so it's due on 2 March. An invoice dated 30 January on the same term is due on 2 March as well.
In practice, this means a month's invoices fall due together, which suits a client who pays in runs. However, it also gives an invoice issued early in the month nearly twice the time its name suggests. I recommend checking which of the two you agreed to before you chase it.
Calendar days or working days
Standard Net terms are calendar days. Counting in working days means Monday to Friday only, which is what a phrase like "within 10 business days" describes, and it always lands the due date on a weekday. For a working-day count on its own, away from payment terms, counting working days explains why two sensible counts differ by 1, and the business days calculator runs it.
The calculator has no public holiday table. This is because holidays depend on the country, often on the region inside it, and on the year. Skipping the wrong country's holidays would give a wrong date that looks reliable. If your terms exclude holidays, I recommend taking them off by hand from the date the calculator gives you.
A due date that lands on a weekend
A weekend due date stays on the weekend unless your agreement moves it. In calendar mode the calculator leaves it there, because that is what the term says, and names the next working day beside it. Some agreements move a weekend or holiday due date to the next working day. Plenty don't, and under terms that say nothing, a payment arriving on the Monday is late by the letter of the agreement.
If it matters to you, I'd put the rule in writing before the first invoice, not after the first late one.
Short version: add the days in the term to the invoice date, which is day zero. Net 30 on an invoice dated 1 August is due on 31 August. End-of-month terms count from the last day of the invoice month, so Net 30 EOM on an invoice dated 2 January is due on 2 March.
Last updated 23 September 2026