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Late payment interest calculator

When a business pays your invoice late, the law in the UK and the EU gives you interest and a fixed sum on top, whether or not your terms mention it. Most small businesses never claim it because they don't know the rate for that half-year or the band. Enter the invoice and get the numbers and a paragraph for the email.

Try:

Where Invoice amount, before interest Due date Paid date (blank: still unpaid, counted to today) Invoice number (optional) Who you write to (optional) Bank of England base rate, % (blank: from the table) Fixed sum (blank: the standard one)

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The rates and bands it uses

UK: 8 points over the Bank of England base rate on 30 June (invoices due July to December) or 31 December (due January to June). Due in the second half of 2026: 3.75% + 8 = 11.75% a year. It is simple interest from the day after the due date, so £4,800 for 45 days is £69.53.
UK fixed sum, per invoice: £40 under £1,000, £70 from £1,000 to £9,999.99, £100 from £10,000. Reasonable collection costs beyond that can be claimed too.
EU: the ECB main refinancing rate on the first day of the half-year plus at least 8 points, and at least €40. Second half of 2026: 2.40% + 8 = 10.40%; first half: 2.15% + 8 = 10.15%. Countries can go higher (change the margin and fee above).
Past half-years: the table runs from 2022. UK total rate: 2023 11.50% then 13.00%, 2024 13.25% twice, 2025 12.75% then 12.25%, first half 2026 11.75%.
Not covered: consumers, a contract that sets its own substantial rate, and debts due after 2026 (the rate isn't published yet; type the base rate and it works).

The email that gets the invoice paid in the first place, and when to send the reminder: The invoice email that gets paid. This is a calculator, not legal advice.

A separate address for invoices and reminders

An email59 mailbox keeps invoice replies in one place instead of someone's own inbox.

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