Invoice Due Date Calculator

How the due date is worked out

Net terms count calendar days from the invoice date. Day 1 is the day after the invoice date, so an invoice dated September 1, 2026 on Net 30 is due on Thursday, October 1, 2026. Saturdays, Sundays and public holidays count like any other day.

End of month (EOM) terms start counting on the last day of the month the invoice is dated in. An invoice dated February 10, 2026 on 30 Days EOM counts from February 28, 2026 and is due on Monday, March 30, 2026. The Cambridge Business English Dictionary entry for net 30 EOM reads: “abbreviation for net 30 days end of month: written on an invoice to show that it must be paid within 30 days of the beginning of the following month” (checked September 25, 2026).

Some businesses count EOM the other way round: they take the invoice date plus the days and use the last day of the month that lands in, Tuesday, March 31, 2026 in this example. A French ministerial answer on 45 days end of month describes both methods and says the one used has to be agreed in advance (Assemblée nationale, checked September 25, 2026). If your customer counts differently, agree on one date.

How to use the calculator

1. 1

   Enter the invoice date

   Use the date printed on the invoice, or the day your contract counts from, such as delivery.

2. 2

   Choose the payment terms

   Net terms count from the invoice date, EOM terms from the end of the invoice month.

3. 3

   Decide what happens on a weekend

   Leave the date as it is, push it to the following Monday or bring it forward to the preceding Friday. Public holidays are not checked.

4. 4

   Put the date on the invoice

   Print the due date next to the terms, so your customer does not have to work it out.

Due dates for every term in the list

For an invoice dated Thursday, January 15, 2026, with weekend dates kept:

When no due date was agreed

Where no payment date was agreed, some rules start the clock when the customer receives the invoice, not on the invoice date:

• United Kingdom, business to business: “If you do not agree a payment date, the law says the payment is late 30 days after either: the customer gets the invoice; you deliver the goods or provide the service (if this is later)” (GOV.UK, checked September 25, 2026)
• European Union, business to business: member states have to ensure, “where the date or period for payment is not fixed in the contract, that the creditor is entitled to interest for late payment upon the expiry of any of the following time limits: (i) 30 calendar days following the date of receipt by the debtor of the invoice or an equivalent request for payment” (Directive 2011/7/EU, Art. 3(3)(b)(i), EUR-Lex, checked September 25, 2026). The directive is addressed to EU countries: a business follows its own country's law that puts it into effect.
• United States (federal agencies): “The period available to an agency to make timely payment of an invoice without incurring an interest penalty shall begin on the date of receipt of a proper invoice” (5 CFR 1315.4(f), eCFR, checked September 25, 2026)

Related tools

• Net 30 Calculator: Net 30 with a 2/10 early payment discount.
• Invoice Number Generator: numbers for your next invoices.
• Free Invoice Generator: put the due date and your terms on a PDF invoice.