Court Interest Calculator UK: Judgment Debt Tool

Overview

A court interest calculator is a simple utility that computes interest accruing on a sum of money between two dates. It is most commonly used in three situations in England and Wales: adding interest to a money claim under section 69 of the County Courts Act 1984 (or section 35A of the Senior Courts Act 1981 in the High Court), calculating interest on commercial debts under the Late Payment of Commercial Debts (Interest) Act 1998, and working out post-judgment interest on a County Court Judgment.

Each of these has its own rate. The statutory rate on judgment debts of £5,000 or more is currently 8% per annum under the Judgments Act 1838, though the rate that applies to your situation depends on the cause of action, the contract between the parties, and whether you are operating under the commercial debt regime.

This calculator lets you plug in whichever rate applies and produce a figure in seconds. It does not decide which rate is correct for you, that part is up to you or the court.

Key steps

1. Pick the correct interest rate. Before you calculate anything, work out which rate applies. For most consumer claims and general money claims, courts commonly award 8% per annum on the principal. For commercial debts between businesses, the late payment legislation adds a higher statutory rate plus the Bank of England base rate. If a contract specifies its own rate, that usually takes priority. Check the paperwork before you type a number in.
2. Choose whether the rate is annual or monthly. The calculator accepts both. Most statutory rates are expressed per year, so leave it on 'Year' unless you have a specific reason to use a monthly figure, such as a contractual term that sets out monthly interest. Mixing the two up is a common error that produces wildly inflated or understated numbers, so double-check this setting before you hit calculate.
3. Enter the start date carefully. Interest usually runs from the date the debt became due, not the date of the invoice and not the date you decided to chase it. For a County Court Judgment, post-judgment interest runs from the date of judgment. For a breach of contract, it typically runs from the date of breach. Getting this date right matters because every extra day adds to the total, and a defendant may challenge an inflated start date.
4. Enter the end date. For a money claim, this will normally be the date you issue proceedings, because interest up to that point is pleaded as a sum, and interest after that is pleaded as a daily rate. For settlement negotiations, use the date you expect payment to be made. For enforcement, use today's date or the date of your application.
5. Enter the principal and calculate. Type in the original debt figure, without any interest already added, and press Calculate. The result shows the interest accrued between your two dates at the rate you selected. Write this figure down alongside the daily rate, because on a claim form you typically need to show both the interest accrued to the date of issue and the daily rate continuing thereafter.

Common questions