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Late Payment Interest Calculator UK
Estimate statutory interest, fixed compensation and the total owed on an overdue UK B2B invoice.
Qualifying B2B debts only. Check the contract and reference period. Fact-checked 26 September 2026.
Calculate your late-payment estimate
Enter two figures below. Your result updates automatically.
The 3.75% reference rate applies from 1 July to 31 December 2026. Change this for a debt that became late in another six-month period.
Check the debt qualifies before adding charges
This estimate is for late commercial payments between businesses, not consumer debts. If your contract sets a different substantial remedy or interest rate, statutory interest may not apply. Use the reference rate for the six-month period in which the debt became late.
How Late Payment Interest Works in the UK
Under the Late Payment of Commercial Debts (Interest) Act 1998, suppliers may charge statutory interest on qualifying overdue business-to-business (B2B) invoices. A different substantial remedy in the contract can change that entitlement.
Statutory Interest Rate
The statutory interest rate is 8% per annum above the Bank of England base rate. This interest accrues daily from the day after the payment due date.
Fixed Compensation
In addition to interest, you can claim a fixed sum as compensation for debt recovery costs:
Proposed 2026 Late Payment Reforms
The Commercial Payments Bill was introduced to Parliament in May 2026. Proposed measures include maximum payment terms, mandatory interest on late payments, stronger reporting requirements and new enforcement powers for the Small Business Commissioner.
These changes are not yet in force. The government says businesses will receive a lead-in period and the measures will not apply retrospectively.
Review a reminder for an existing invoice
Experi estimates late-payment interest and compensation for an eligible B2B debt. Check the contract and applicable reference period before adding any charge.
Frequently Asked Questions
What is the statutory interest rate for late payment in the UK?
The statutory interest rate for late commercial payments is 8% above the applicable Bank of England reference rate. The 3.75% rate on 30 June 2026 applies from 1 July to 31 December 2026, giving an annual statutory rate of 11.75% for that period.
How much fixed compensation can I claim for a late payment?
For an eligible late commercial payment, fixed compensation is £40 for debts up to £999.99, £70 for debts between £1,000 and £9,999.99, and £100 for debts of £10,000 or more.
When does an invoice become overdue?
An invoice becomes overdue the day after the agreed payment terms expire. If no terms are specified, the default payment period is 30 days from either the delivery of the invoice or the delivery of the goods/services, whichever is later.
Can I add late payment interest to an MCOL claim?
For an eligible business-to-business unpaid invoice, statutory interest and fixed compensation can be part of the amount owed. Keep a copy of the invoice, payment terms, reminder emails, and the calculation so you can show how the claim amount was worked out.
What is the 2026 Late Payment Reform?
The Commercial Payments Bill was introduced to Parliament in May 2026, but its measures are not yet in force. The Bill proposes maximum payment terms, mandatory interest, stronger reporting and enforcement powers, with a transition period before commencement.
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