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Statutory Interest Calculator

Interest on a late invoice or judgment: UK late payment at base rate + 8%, the UK 8% judgment rate, or an ECB, US federal or custom rate, simple or compounded. How it works

Use the Statutory Interest Calculator

Directive 2011/7/EU: simple interest at the ECB reference rate plus at least 8 percentage points

Enter the current ECB reference rate

Directive 2011/7/EU: at least 8 percentage points over the ECB rate

Compounding
Total statutory interest
Enter the details
Total owed —

About the Statutory Interest Calculator

A £5,000 UK judgment debt at the 8% judgment rate earns £400.00 of simple interest from 1 March 2025 to 1 March 2026, or £1.10 a day. A £10,000 UK business invoice paid 62 days late earns £199.59 at the late-payment rate of 3.75% base rate + 8%, plus a £100 fixed sum. The statutory interest calculator works out interest on any principal at the UK judgment or late-payment rate, an ECB or US federal rate you type, or a custom rate, as simple interest or compounded annually, monthly or daily.

10,000 at 8% for four years, by accrual

AccrualInterestTotal owed
Simple3,202.1913,202.19
Annual3,607.6513,607.65
Monthly3,756.6613,756.66
Daily3,773.8113,773.81

1 January 2022 to 1 January 2026 is 1,461 days. Simple interest divides by 365, so the leap day in 2024 adds one day of interest.

How to use this tool

  1. Pick a jurisdiction: EU, UK judgment rate, UK late payment (invoice), US federal or Custom Rate. The choice sets the currency and the usual accrual.
  2. Enter the principal and, for the EU, US or UK late payment, the reference rate in force. The tool does not look rates up.
  3. Enter the start date (counted) and the end date (not counted). For UK late payment, enter the invoice date, the payment days and the payment date instead; the tool works out the due date and the days late.
  4. Pick Simple, Annual, Monthly or Daily (UK late payment is always simple). The result updates as you type.
  5. For a late UK business invoice, set Add fixed compensation to Yes to include the Late Payment Act fixed sum in the total owed.
  6. Read the interest, the total owed, the daily accrual and the year-by-year table.

Frequently asked questions

What is the interest rate on a UK judgment debt?
8% a year, simple, under section 17 of the Judgments Act 1838. The Judgment Debts (Rate of Interest) Order 1993 cut it from 15% to 8% from 1 April 1993. Pick UK and the rate and Simple accrual are filled in.
How do I calculate late payment interest under the Late Payment of Commercial Debts Act?
Pick UK late payment (invoice, base rate + 8%). Interest is simple, at 8% over the Bank of England base rate, from the day after the due date to the day of payment. The base rate is the one in force on 30 June for interest that starts from July to December, or on 31 December for January to June, and it stays the same for the whole debt. The tool counts the payment days as a period beginning with the invoice date, so £10,000 invoiced on 1 July 2026 on 30 days is due on 30 July; paid on 30 September it is 62 days late, and at 3.75% + 8% = 11.75% the interest is £199.59. With no agreed payment date, the Act makes the debt due on the last of the 30 days beginning with the later of delivery and the buyer’s notice of the amount, so enter that later day as the invoice date and 30 payment days.
What fixed compensation can I add to a late invoice in the UK?
Section 5A of the Late Payment of Commercial Debts (Interest) Act 1998 gives the supplier a fixed sum per invoice on top of the interest: £40 for a debt under £1,000, £70 from £1,000 to under £10,000 and £100 from £10,000. With UK late payment selected, set Add fixed compensation to Yes: the 62-day £10,000 invoice above earns £199.59, and the £100 sum makes £10,299.59 owed. It applies to business-to-business debts under that Act, not to judgment interest.
How is EU late payment interest worked out?
Directive 2011/7/EU sets simple interest at the ECB main refinancing rate plus at least 8 percentage points. The rate in force on 1 January applies to the first half of the year and the one on 1 July to the second. Type the reference rate; with 2.00% and the 8-point margin, 10,000 from 1 January to 1 April 2024 earns 249.32.
How does US federal post-judgment interest work?
28 U.S.C. § 1961 uses the weekly average 1-year constant maturity Treasury yield for the week before the judgment, computed daily and compounded annually. Type that yield; the US preset uses Annual accrual. It covers federal court judgments only, not state judgments.
Why does daily compounding give more than simple interest?
Each day’s interest is added to the balance and earns interest itself. On 10,000 at 8% for four years, simple interest is 3,202.19 and daily compounding 3,773.81.

Interest on late payments and judgments

A £5,000 UK judgment debt at the 8% judgment rate, from 1 March 2025 to 1 March 2026, earns £400.00 of simple interest: £335.34 in 2025 and £64.66 in 2026, or £1.10 a day.

For a late UK business invoice, pick UK late payment (invoice, base rate + 8%) and enter the invoice date, payment days, payment date and base rate. Payment days run from the invoice date, as in the Act: £10,000 invoiced on 1 July 2026 on 30 days is due on 30 July. Paid on 30 September 2026 it is 62 days late: at 3.75% + 8% = 11.75% it earns £199.59, and the £100 fixed sum makes £10,299.59 owed.

Rates by jurisdiction and how the tool applies them

Simple interest is principal × rate × days ÷ 365, counting the start date but not the end date. Annual mode adds the interest on each anniversary, daily mode compounds rate ÷ 365 a day and monthly mode rate ÷ 12 a calendar month.

  • EU: Directive 2011/7/EU, simple, at the ECB main refinancing rate in force on 1 January or 1 July plus at least 8 points.

  • UK judgment: 8% a year, simple, under section 17 of the Judgments Act 1838 (SI 1993/564).

  • UK late payment: simple interest from the day after the due date, at 8% over the base rate in force on 30 June for interest that starts from July to December, or on 31 December for January to June (SI 2002/1675, article 4). The default 3.75% was the rate on 30 June 2026.

  • US federal: 28 U.S.C. § 1961, the weekly average 1-year Treasury yield for the week before the judgment, compounded annually.

Section 5A of the 1998 Act adds a fixed sum per invoice: £40 under £1,000, £70 from £1,000 to under £10,000, £100 from £10,000. Leave Add fixed compensation off for a judgment debt. Rates are typed, not looked up.

Fun Fact: English judgment debts have carried 8% since 1 April 1993, down from 15%.

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