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Late payment interest calculator

Work out exactly what a late-paying customer owes you: the statutory interest (8% above the Bank of England base rate) plus the fixed compensation you're entitled to under the Late Payment of Commercial Debts Act 1998.

£
Statutory rate = 8% + base rate. Base rate is 3.75% as of July 2026 (check current). For a fixed 6-month reference, use the base rate on 30 June or 31 December.
Total you can claim
£0.00
on top of the £0.00 invoice
Days overdue0
Statutory interest£0.00
at 11.75% · £0.00/day
Fixed compensation£0.00
Total with the invoice£0.00

The interest keeps building every day it goes unpaid. Change the dates or amount and the numbers update instantly.

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How late payment interest works in the UK

If you invoice another business and they pay late, you have a legal right to interest and compensation, whether or not it's written into your terms. It's set by the Late Payment of Commercial Debts (Interest) Act 1998, and it applies to business-to-business sales (not to consumers).

1. Statutory interest

You can charge 8% plus the Bank of England base rate, worked out day by day from the day after payment was due. With the base rate at 3.75%, that's 11.75% a year. On a £5,000 invoice that's about £1.61 a day, so it adds up fast on a big job left unpaid.

2. Fixed compensation

On top of the interest, each overdue invoice carries a fixed sum for the hassle of chasing it:

If chasing the debt cost you more than that (for example a debt-recovery agency), you can claim the reasonable extra cost too.

3. When the clock starts

Interest runs from the day after the agreed payment date. If you never agreed a date, the default is 30 days after the customer received the invoice, or the goods or service, whichever is later.

Common questions

Do I need it in my contract to charge interest?

No. Statutory interest and compensation apply automatically to commercial debts. You don't need a late-payment clause, though you can set your own rate in a contract if it's a genuine remedy.

Does this apply to consumers?

No. The Late Payment Act covers business-to-business and business-to-public-sector transactions. Charging a private consumer works differently and is governed by your contract and consumer law.

Should I actually charge it?

Many firms use the figure as leverage in a chaser rather than always enforcing it, but the right is real and you can pursue it, including through the small claims track. Even mentioning statutory interest and compensation in a reminder often gets an overdue invoice paid.

What about VAT?

Statutory interest and compensation are not consideration for a supply, so they're outside the scope of VAT. Calculate interest on the amount actually outstanding.

This calculator is a free tool for general guidance and isn't legal or financial advice. The statutory rate is fixed in six-month reference periods to the Bank of England base rate on 30 June and 31 December; for a formal claim, check the correct reference-period rate and consider taking advice on your specific situation.

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