Free calculator
Late payment interest calculator
Enter the invoice amount, when it was due and when it was paid (or today). You get the interest you can claim, by the day, and the fixed compensation.
Interest and compensation
£166.58
- Invoice amount
- £5,000.00
- Interest: 60 days at 11.75% (8% + 3.75% on 30 June 2026)
- £96.58
- Fixed compensation
- £70.00
- Total you can claim
- £5,166.58
Interest adds £1.61 for each further day.
Your right to interest
Under the Late Payment of Commercial Debts (Interest) Act 1998, a business paid late by another business can claim statutory interest of 8% a year above the Bank of England base rate, unless your contract sets a different rate.
The base rate used is the one on 31 December for debts that become late between January and June, and the one on 30 June for debts that become late between July and December. It stays fixed for the whole debt.
With the base rate at 3.75% on both reference dates, statutory interest is 11.75% a year for debts that became late in 2026. Interest is simple: the amount × the rate ÷ 365 for each day late.
Fixed compensation
- Up to £999.99: £40
- £1,000 to £9,999.99: £70
- £10,000 or more: £100
When a payment is late
After the date you agreed. When nothing was agreed, 30 days after the customer received your invoice or the goods or services, whichever is later.
Base rates: Bank of England: Bank Rate history, checked 30 September 2026.
Last updated 2026-10-01. This calculator is a guide, not tax advice.
Frequently asked questions
Can I charge late payment interest to consumers?
No. The 1998 Act covers business-to-business debts only.
Do I need to warn the customer first?
The right to statutory interest comes from the Act, but saying so on your invoices helps: Invoice Native can print a late payment clause on every UK invoice.
Is the Commercial Payments Bill law yet?
Not yet. It would cap payment terms at 60 days and make late payment interest mandatory; this calculator follows the current 1998 Act.