The Late Payment of Commercial Debts (Interest) Act 1998 lets a business that is paid late by another business or public body claim statutory interest and fixed compensation, whatever the contract says about late payment, provided the contract does not set its own substantial remedy.
Interest is 8% a year above the Bank of England base rate. The base rate used is the one in force on 30 June for invoices that fall due between 1 July and 31 December, and on 31 December for invoices that fall due between 1 January and 30 June. Interest runs from the day after the due date until payment.
You can also claim a fixed sum for the cost of recovery: £40 for debts under £1,000, £70 for debts from £1,000 to £9,999.99, and £100 for debts of £10,000 or more.
This applies to business-to-business and public-sector contracts governed by UK law. It does not cover consumers. This calculator is a guide, not legal advice, and the result is only as accurate as the dates and amount you enter.