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Late payment interest calculator

A trade customer paid late, or still hasn't. Find out what UK law lets you add to the bill: statutory interest, plus a fixed sum for every late invoice.

Did you agree a payment date?
Change the Bank of England reference rate

Filled in for you from the date interest starts. Only change it if you know the rate that applies is different.

What you can claim

Enter the amount and dates to see what you can claim.

How the calculation works

The Late Payment of Commercial Debts (Interest) Act 1998 lets a business add interest and compensation when another business pays late, unless your contract sets its own late-payment terms. It applies across England, Wales, Scotland and Northern Ireland.

  • Interest is 8% a year over the Bank of England reference rate. It's simple interest, worked out per day: amount × rate ÷ 365 × days late.
  • The reference rate is the Bank Rate on 31 December for interest that starts between January and June, or on 30 June for July to December. It then stays fixed for that invoice, even if the Bank changes the rate later.
  • Interest starts the day after payment was due. If you didn't agree a date, payment is due 30 days after you delivered or invoiced, whichever was later.
  • Fixed compensation is added once per invoice: £40 for invoices under £1,000, £70 up to £9,999.99 and £100 for £10,000 or more. You can also claim reasonable extra costs of recovering the debt.

Reference rates

Interest startsReference rateStatutory rate

Before you send a claim

  • It's for business-to-business sales only, not sales to consumers.
  • Check your terms. If your contract has its own interest rate or late fee, that applies instead.
  • Send a new invoice or statement showing the interest and compensation, with how to pay.
  • Many suppliers waive the interest for a good customer who pays straight away. Knowing the figure helps that conversation.

This calculator is a guide, not legal advice. For the official rules see gov.uk: late commercial payments, and for the rate history see the Bank of England.