The 8% statutory interest calculator.

Calculate the 8% interest you can add to a small claims court debt. Working calculator for discretionary interest under section 69 County Courts Act 1984.

Calculate your interest

Days since debt fell due

Interest requested at 8%

Principal plus requested interest

You can request interest until judgment or earlier payment. The court decides the rate and period. Post-judgment interest follows separate rules and is not automatic on a small claim. Use the unrounded daily rate when calculating the total.

This estimates a request at 8% a year under section 69 of the County Courts Act 1984, which gives the court discretion over the rate and period. It does not set an automatic 8% entitlement. Qualifying commercial debts have separate late-payment rules at 8 percentage points above the applicable Bank of England reference rate.

When you can add interest

• Unpaid invoices — from the date the invoice was due (typically 30 days from issue, or as stated in the contract).
• Loans not repaid — from the date repayment was due under the loan agreement.
• Goods returned for refund but not refunded — from the date the refund became legally due.
• Deposit not returned — from the date the trader was obliged to return it (end of tenancy, completion of work, etc.).
• Damages for breach of contract — from the date the breach caused you the loss.

Including interest in your claim

Interest must be claimed explicitly on the claim form. On the N1 form or the online Money Claim form, complete the interest section by ticking the box for section 69 of the County Courts Act 1984, stating the daily rate (principal multiplied by 0.08, divided by 365), stating the total accrued from the date the debt fell due to the date you file, and asking that interest continues to accrue at that daily rate from filing through to judgment or earlier payment.

If the defendant pays before judgment, calculate interest through to the date they actually pay. Do not stop at the filing date.

Business debts and the Late Payment Act

For debts between businesses, the Late Payment of Commercial Debts (Interest) Act 1998 applies instead. The rate is 8% above the Bank of England base rate, not a flat 8%. Check the applicable statutory reference rate for the period of the debt. The Late Payment Act also entitles you to a fixed compensation amount on top: £40 for debts under £1,000, £70 for debts between £1,000 and £9,999, and £100 for debts of £10,000 and over. You cannot use both Acts against the same debt, so for business debts the Late Payment Act is usually the better choice when the base rate is high.

As a worked example: the defendant owes £3,500, due on 1 March 2025, filing date 1 June 2026 (457 days). At 8%, the unrounded daily rate is £3,500 × 0.08 ÷ 365 = £0.767123… . For 457 days, requested interest is £350.58, making £3,850.58 before fees. Round the total only after multiplying, and request further interest to judgment or earlier payment, subject to the court’s discretion. This example uses section 69, not the commercial-debt rate.