Late Payment Interest Calculator
The interest you can charge on a late invoice, per day and in total.
Good to know. Statutory interest is less about the money than the message: invoices are due when they say they are.
Not financial advice. Uses only the numbers and rates you enter — no live data.
How it works
In plain words
Divide the yearly rate by 365 for the daily rate, multiply by the invoice amount for the interest per day, and by the days between the due date and payment. Simple interest, not compound. UK law adds a fixed sum per invoice: £40 under £1,000, £70 under £10,000 and £100 above.
The formula
interest per day = amount × rate ÷ 365 interest = interest per day × days late UK compensation: £40 (< £1,000), £70 (< £10,000), £100
Worked example
A 5,000 invoice paid 59 days late at 12% a year: 5,000 × 12% ÷ 365 = 1.64 a day, so 96.99 of interest, plus £70 fixed compensation.
Sources
- GOV.UK, Late commercial payments: charging interest and debt recovery The 8% over base rate, the reference dates and fixed compensation of £40, £70 and £100.
- Directive 2011/7/EU on combating late payment in commercial transactions The EU rate of the ECB reference rate plus at least 8%, and €40 compensation.
Sources checked September 30, 2026. 4 automated tests check its answers on every change.
About the late payment interest calculator
When a business pays another business late, the law in the UK and across the EU lets the supplier charge interest and a fixed sum towards the cost of chasing the debt, even if the contract says nothing about it. This calculator works out the interest from the invoice amount, the days it is overdue and the yearly rate.
In the UK, the Late Payment of Commercial Debts (Interest) Act 1998 sets statutory interest at 8% a year above the Bank of England base rate. The base rate used is the one on 31 December for debts due in the first half of the year and on 30 June for the second half. Add £40, £70 or £100 of fixed compensation per invoice, depending on its size. In the EU, the late payment directive sets a similar rate of the ECB’s main rate plus at least 8%, and a €40 minimum.
Interest runs from the day after the due date, which is 30 days after the invoice if no date was agreed, until payment. It is simple interest on the invoice amount. If a contract sets its own rate, that applies instead, as long as it is a fair remedy.
Statutory interest applies between businesses, not to consumers. Sending a polite reminder that mentions it is often enough to get paid.
Questions people ask
How much interest can I charge on a late invoice in the UK?
8% a year above the Bank of England base rate, plus £40, £70 or £100 fixed compensation per invoice.
When does late payment interest start?
The day after the payment was due. Without an agreed date, 30 days after the invoice or delivery.
Can I charge late payment interest to consumers?
Not under the statutory scheme, which is for business-to-business debts. You can only charge consumers interest if the contract allows it.