UK Late Payment Interest Calculator

Use this free UK late payment interest calculator to estimate statutory interest on overdue invoices, late payments, and unpaid business debts.

Estimate statutory interest on overdue UK business invoices using the annual rate of Bank of England base rate plus 8%.

Invoice amount (£) Bank of England base rate (%) Invoice due date Payment date

This calculator is for general information only and does not constitute legal, financial, or professional advice.

How UK late payment interest is calculated

In the UK, statutory late payment interest for business debts is usually calculated using the Bank of England base rate plus 8%. This is commonly used for overdue business invoices where payment has not been made by the agreed due date.

The basic formula is:

Interest = Invoice amount × Annual interest rate × Days overdue ÷ 365

For example, if an invoice of £1,000 is 30 days overdue and the Bank of England base rate is 5.25%, the statutory annual interest rate is 13.25%. The estimated interest would be £10.89.

This calculator is designed for general guidance only. It does not replace legal, financial, accounting, or professional advice. Always check the latest Bank of England base rate and the terms of your contract before relying on any calculation.