Free tool
UK Late Payment Interest Calculator
Work out what a client legally owes you under the Late Payment of Commercial Debts (Interest) Act 1998 — statutory interest plus fixed compensation.
Rules and defaults change based on jurisdiction.
Check the current rate at bankofengland.co.uk before relying on this figure. It changes periodically and this field does not update automatically.
Days overdue31 days
Statutory interest rate (base + 8%)11.75% per annum
Interest accrued£19.96
Fixed compensation (Late Payment Act)£70.00
Total additional amount owed£89.96
Most invoicing tools don't calculate this for you.
Tallylark sends escalating payment reminders automatically, so you're less likely to need this calculator in the first place.
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This calculator applies the statutory formula under the Late Payment of Commercial Debts (Interest) Act 1998 for business-to-business debts in England, Wales, and Northern Ireland (Scotland has separate but similar provisions). It is provided for information only and is not legal or financial advice. Fixed compensation bands: £40 for debts under £1,000, £70 for £1,000–£9,999, £100 for £10,000 and over. Interest is calculated as simple interest on the outstanding amount from the day after the due date. If a contract specifies a different payment term or interest rate, the contract terms may take precedence. Check your own agreement or get professional advice for anything disputed or high-value.