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Work out what a late payment is actually costing you.
UK law entitles you to statutory interest and a fixed sum on top of any overdue commercial payment. Most businesses never claim it. No signup, and nothing is stored.
Enter an amount and a due date to see what you can claim.
Calculated as simple interest, daily, on a 365-day year, which is how the Act is applied in practice. This is general information, not legal advice. The official position is on gov.uk.
How this works
What is the UK statutory late payment interest rate?
Bank of England base rate plus 8 percentage points, under the Late Payment of Commercial Debts (Interest) Act 1998. For debts becoming late between 1 July and 31 December 2026 that is 11.75 per cent, using the 3.75 per cent base rate in force on 30 June 2026.
Does the rate change every time the base rate changes?
No, and this is where most calculators go wrong. The rate is fixed for six-month periods. Debts becoming late between 1 January and 30 June use the base rate in force on the previous 31 December; debts becoming late between 1 July and 31 December use the rate in force on 30 June. It then holds for that whole period.
Can I claim compensation as well as interest?
Yes. The same Act sets a fixed sum on top of interest: £40 for debts under £1,000, £70 for £1,000 to £9,999.99, and £100 for £10,000 and above. If your reasonable recovery costs exceed that fixed sum, you can claim the difference.
When does interest start running?
The day after payment was due, and it runs until the debt is paid. If you agreed payment terms, that is the agreed date. If you did not agree any, the default is 30 days after delivery or after the customer received the invoice, whichever is later.
Does claiming interest mean going to court?
No. The entitlement is automatic and you can state it on a statement or in a chase email. Most businesses never charge it, and mentioning that you are entitled to often moves a payment on its own.
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