This tool gives you an instant estimate to help you understand what you're owed: it's information, not legal advice. We are not solicitors. Figures are only as accurate as what you enter, and statutory rates can change; confirm anything you rely on before sending it to a client or a court.
Use this late payment calculator to work out exactly what a late-paying client owes you under UK law: statutory interest, the fixed late payment compensation charge, and the total. Enter your invoice details below; everything updates instantly, and nothing is sent anywhere until you choose to use it.
Your invoice
+ 8% = 11.75% statutory rate
Pre-filled with the current rate (3.75%, checked 5 July 2026), editable, since the Bank of England can change it at any Monetary Policy Committee decision. See the current Bank Rate before relying on this if it's been a while.
What's owed
Statutory interest£0.00
Fixed compensation£0.00
Total now due£0.00
Simple interest, not compound: calculated daily on the original invoice amount only. Fixed compensation: £40 under £1,000, £70 from £1,000 to £9,999.99, £100 at £10,000 or more.
Add this to a chase letter →
Don't just calculate it; send it. Carry these figures straight into a properly worded chase letter, with the statutory basis already stated correctly.
Copy the interest paragraph
Ready to paste straight into an email or letter: states the statutory basis and the figures, so a client sees you know exactly what you're owed and why. If you're recalculating this every week across several invoices, that's usually the point people move off a spreadsheet and into accounting software like Sage(affiliate).
Interest paragraph
Under the Late Payment of Commercial Debts (Interest) Act 1998, this invoice now attracts statutory interest at 11.75% a year (the Bank of England base rate of 3.75%, plus 8%), calculated daily from the day after the due date until payment is received in full.
As of today, that is £0.00 in statutory interest, plus fixed compensation of £0.00 for the cost of recovering this debt.
The total now due is £0.00, not the original invoice amount of £0.00 alone.
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How this late payment calculator works
Statutory interest under the Late Payment of Commercial Debts (Interest) Act 1998 is simple interest, not compound: invoice amount × statutory rate ÷ 365 × days overdue. The statutory rate is the Bank of England base rate plus a fixed 8%, and it only applies to qualifying business-to-business debts.
On top of interest, you can add fixed compensation: £40, £70, or £100 depending on the size of the debt, without needing to prove you spent that much recovering it. This calculator adds both together automatically, so the figure it shows is the full amount now owed, not just the interest.
Worked example
Say you invoiced a client £3,200 and it's now 45 days overdue, with the Bank of England base rate at 3.75%. The statutory rate is 11.75% a year (3.75% + 8%). Interest works out as £3,200 × 11.75% ÷ 365 × 45 days, plus £70 fixed compensation, since the debt is between £1,000 and £9,999.99. Try those exact numbers in the calculator above to see the full total.
Multiply the overdue invoice amount by the statutory interest rate, divide by 365, then multiply by the number of days overdue. The statutory rate is the Bank of England base rate plus 8%, and it is simple interest, calculated daily on the original invoice amount only, not compound interest. This calculator does that sum for you and adds the fixed compensation you can also claim.
Under the Late Payment of Commercial Debts (Interest) Act 1998, the statutory rate is the Bank of England base rate plus 8% a year. With the base rate currently 3.75%, that is 11.75% a year (checked 5 July 2026). This only applies to business-to-business debts; it does not apply to consumers.
Yes: this calculator is free, requires no signup, and works out both the statutory interest and the fixed compensation charge (£40, £70, or £100 depending on the debt size) that a UK business can add to an overdue invoice under the Late Payment of Commercial Debts (Interest) Act 1998.
On top of interest, UK law lets you add a fixed compensation charge without proving what it cost you to chase the debt: £40 for debts under £1,000, £70 for debts from £1,000 up to £9,999.99, and £100 for debts of £10,000 or more.
Yes. Statutory interest and compensation under the Late Payment of Commercial Debts (Interest) Act 1998 apply automatically to qualifying business-to-business debts, whether or not your contract or invoice mentions interest. A contract can only vary this right upward or in ways that remain fair to the supplier, never remove it.
Yes. Enter either the invoice due date or the number of days it has been overdue, and an invoice amount; the calculator works out interest and compensation as of today. You can also edit the base rate field if you are calculating for a period when the Bank of England rate was different from today's.
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