Free tool
Late payment interest calculator
Estimate simple statutory interest and the fixed recovery sum for one overdue commercial invoice.
Check that this tool fits your invoice
For one qualifying UK commercial invoice with an unchanged principal. Use the actual due date, not simply the invoice date. For disputed debts, instalments, credit notes, partial payments or contractual interest, obtain a tailored calculation. Read our guide to your late-payment rights.
YOUR ESTIMATE
Interest and compensation
If the principal has already been paid, do not request it again: only eligible unpaid additional charges may remain. The fixed sum is included once for this debt. Additional reasonable recovery costs and court fees are excluded. Interest is rounded once, not daily. This calculation does not decide legal entitlement or time limits.
Free to use. No account needed. Calculation amounts, rates and dates stay in your browser and are not sent to FindCompany.
How this estimate works
Interest = invoice amount × ((reference rate + 8) ÷ 100) × days late ÷ 365
The first late day determines the reference date: the preceding 31 December for January–June, or 30 June for July–December. This tool keeps that rate for the debt, following article 4 of the 2002 Order and the Scottish equivalent.
The verified 2026 reference values are 3.75%, based on the Bank’s December 2025 decision and June 2026 decision. No live rate lookup is made when you calculate.
For an overdue qualifying debt, the fixed sum is £40 below £1,000, £70 from £1,000 to £9,999.99, or £100 from £10,000. No interest or fixed sum is included if the calculation date is on or before the due date. See GOV.UK recovery-cost bands.
For illustration, £2,500 at a 3.75% reference rate plus 8 percentage points for 30 days produces £24.14 interest, plus £70 fixed compensation: £94.14 in additional charges.
General information, not legal advice or a formal demand. This tool supports due dates from 16 March 2013; that does not establish whether the amended rules apply to your contract or whether an older debt is still enforceable. Limitation and Scottish prescription rules differ. Get advice on older debts, foreign contracts and disputed rights.