Not late on . Interest starts the day after the due date.
- Days late
- Rate
- (8% plus on )
- Interest
- Per day now
- Fixed sum
Late payment interest calculator
Type in an overdue invoice. See the statutory interest and fixed compensation you may be able to claim from a business customer.
For a debt that becomes late now, the rate is 11.75% a year: 8% plus the Bank of England Bank Rate of 3.75% in force on 30 June 2026.
You may be able to claim
Interest so far
Fixed compensation
Total with the debt
Interest grows by a day while the debt is unpaid.
This applies only when all of these are true
Want this worked out for every overdue invoice, with the letter ready to approve?
Upload your aged debtorsHow the calculation works
Interest starts the day after the agreed payment date. It is simple interest at 8% a year over the Bank of England rate in force on the 30 June or 31 December before interest starts. The rate stays fixed for that debt. This calculator works the exact figure and rounds once, so it can differ by pennies from a calculator that rounds the daily figure first.
Once interest starts, you may also claim a fixed sum per invoice: £40 for a debt under £1,000, £70 from £1,000 to under £10,000, and £100 from £10,000.
You may be entitled to claim only when:
- The debt is between two businesses.
- The contract does not set its own late payment interest.
- The due date is the payment date you agreed.
Legal basis
- Late Payment of Commercial Debts (Interest) Act 1998, section 1: a qualifying debt carries simple interest.
- Section 4: interest starts the day after the relevant day (the agreed payment day).
- Section 5A: a fixed sum of £40, £70 or £100 per debt once interest starts.
- Late Payment of Commercial Debts (Rate of Interest) (No. 3) Order 2002 (SI 2002/1675), article 4: the rate is 8% a year over the Bank of England rate in force on the 30 June or 31 December before interest starts.
Read more on GOV.UK: late commercial payments.