Money Claim Interest Calculator (UK, 8%)

How to do it

1. 1
   Enter the amount owed

   Type the debt without interest.

2. 2
   Enter the start date

   Use the date the debt was due.

3. 3
   Enter the end date

   Leave it blank to use today.

4. 4
   Set the rate

   Use 8 percent for the usual court rate.

5. 5
   Read the interest

   See the days, the daily interest and the total.

About this tool

When you start a county court claim for money owed, you can usually add statutory interest at 8 percent a year, simple interest, from the date the debt was due until the claim is issued or paid. This calculator takes the amount, the start date and the end date, and shows the number of days, the daily interest, the total interest and the total owed. You can change the rate if your contract sets another or if you are working out the interest on a judgment. It helps prepare a letter before action and a claim form.

Who this is for Small businesses chasing unpaid invoices, individuals owed money, and anyone completing a money claim form who needs to state interest.

How the 8 percent works For claims for debt or damages in the county court, the court can award simple interest, usually at the rate of 8 percent a year, under the County Courts Act 1984. It is calculated on the amount owed, not on interest already due, and runs from the date the debt became due. The daily rate is the amount times 8 percent divided by 365. A debt of £4,500 earns £0.99 a day, about £360 a year.

Business debts For commercial debts under the Late Payment of Commercial Debts (Interest) Act 1998, the statutory rate is 8 percent above the Bank of England base rate, plus a fixed sum for compensation of £40, £70 or £100 depending on the size of the invoice. This tool does not add those, but you can enter a different rate to test it.

Using the tool Enter the amount, the date the debt was due and, if known, the date until which you want interest, or leave it blank to use today. Change the rate if needed. You get the days, the daily interest, the total interest, the total owed and the interest per month. When you fill in a claim form, enter the daily rate so that the court can continue to add interest until judgment.

Worked example A debt of £4,500 was due on 1 November 2025. Interest to 1 November 2026 is 365 days at £0.99, which is £360, so the total is £4,860. Interest continues to accrue at £0.99 a day until the debt is paid or judgment is entered.

Next steps Before you issue a claim, send a letter before action that gives the debt, the interest and a deadline, usually 14 to 30 days. Keep the evidence: contract, invoices and messages. Check the court fee and the limits for small claims, which are for claims up to £10,000 in England and Wales.

Limits The court has discretion to award interest, and the details differ for contracts with their own rates and for judgments. This is a calculator and not legal advice.

Worked example

A debt of £4,500 due on 1 November 2025 earns about £0.99 a day at 8 percent, £360 to 1 November 2026, for a total of £4,860.