Free calculator
Invoice due date calculator
Pick the invoice date and your payment terms. The calculator counts the days and gives you the due date and the day of the week.
Due date
30 October 2026
- Day of the week
- Friday
- Days from the invoice date
- 30
How due dates are counted
Payment terms count calendar days from the invoice date, weekends and bank holidays included. An invoice dated 1 March on 30-day terms is due on 31 March.
Print the due date on the invoice itself, not just the terms, so there is no argument about when payment was expected.
The 30-day default
When no payment date was agreed with a business customer, payment is late 30 days after they received your invoice or the goods or services, whichever is later. After that you can claim statutory interest and compensation.
Last updated 2026-10-01. This calculator is a guide, not tax advice.
Frequently asked questions
What are normal payment terms in the UK?
14 or 30 days are common for small businesses. Terms of up to 60 days are usual between businesses; longer terms must be fair to the supplier.
Does a due date on a weekend move?
Not automatically. Many customers pay on the next working day, so you may want to set terms that land on a weekday.
What can I do when an invoice is paid late?
Between businesses you can claim statutory interest at 8% above the Bank of England base rate, plus fixed compensation of £40, £70 or £100 depending on the amount. Our late payment interest calculator works it out.