Late payment interest calculator
Statutory interest on an unpaid invoice, period by period.
Output
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Example
A £4,800 invoice paid 106 days late: statutory interest plus £70 compensation
A web developer invoices a company £4,800, due on 31 March 2026; the money arrives on 15 July 2026. Settings: United Kingdom, “A business, by a business (invoice)”, amount 4800, due 2026-03-31, paid 2026-07-15, no agreed rate.
- Interest runs from the day after the due date, 1 April 2026, to the day of payment: 106 days.
- The rate is 8 % over the Bank Rate on 31 December 2025, 3.75 %: 11.75 % a year, fixed for the whole debt.
- Simple interest by the day: £4,800 × 11.75 % × 106 ÷ 365 = £163.79.
- Fixed compensation is added once: £70 for a debt from £1,000 to under £10,000.
| Invoice | Interest (106 days at 11.75 %) | Compensation | Total to claim |
|---|---|---|---|
| £950.00 | £32.42 | £40.00 | £1,022.42 |
| £4,800.00 | £163.79 | £70.00 | £5,033.79 |
| £12,500.00 | £426.54 | £100.00 | £13,026.54 |
£163.79 interest and £70 compensation: £5,033.79 with the invoice. A rate in the contract replaces the statutory one — at an agreed 4 % the same delay gives £55.76, with no fixed sum added. A guide to the sums, not legal advice.
How it works
- Choose whose law applies and who is owed: a business invoicing a business or a consumer, a private person, or an employee.
- Type the amount and the date it was due, and the date it was paid — leave that empty to count to today.
- The interest appears period by period at the rate then in force, with any fixed compensation and the total to claim.
Frequently asked questions
- How is UK statutory interest worked out?
- Under the Late Payment of Commercial Debts (Interest) Act 1998 a business owed by another business can claim 8% a year over the Bank of England’s reference rate — the Bank Rate on 31 December or 30 June before the interest starts to run — 3.75% on 31 December 2025, so 11.75% for interest that starts in the first half of 2026; Bank Rate was still 3.75% on 30 June 2026, so 11.75% for the second half too. The rate stays fixed for the whole debt, as simple interest by the day, and fixed compensation is added once: £40 under £1,000, £70 under £10,000, £100 above.
- Which rates does it use for other countries?
- Germany: the base rate plus 9 points between businesses (and €40), plus 5 points otherwise. Austria: base rate plus 9.2 points, or 4%. France, Italy and Spain: the ECB rate plus 10 or 8 points between businesses (and €40), otherwise the legal rate. Türkiye, Japan, South Korea and Brazil: their legal rates. A guide to the sums, not legal advice.
- What if the rate changes while the debt is unpaid?
- Each change starts a new line: the days before it at the old rate, the days after at the new one. In the UK and Japan the rate on the day the delay began stays for the whole debt. Rates published up to 31 December 2026 are included; a later period uses the last one known and says so.
- Can I use a rate from the contract?
- Yes: type it and it replaces the law’s rate, as simple interest by the day (by the month for Brazil). Choose “Other” for a country not listed. A penalty clause is added as a percentage of the amount. For a debt between private persons in the UK, where no rate is set by law, type the one you agreed.
- Can I claim statutory interest from a consumer?
- Not under the 1998 Act, which covers debts between businesses. For a consumer or a private loan in the UK the calculator asks for the rate you agreed, and adds no fixed compensation.
- Is anything uploaded?
- No. It is worked out in your browser, and nothing you type leaves your computer.
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