Request a fixed-fee quote →
07503 992804info@dmdcosts.co.ukClient portal
Home / Free tools / Interest on costs calculator
Free tool

Interest on Costs Calculator

Led by Diellza Nika Hyseni and Mentor Nika · Updated 19 October 2026

Work out the interest on an order for costs in England and Wales: 8% a year under the Judgments Act 1838 from the date of the order, or the date the court ordered, with payments on account, the County Court £5,000 rule and a period-by-period table for a letter or the file. From DMD Costs, law costs draftsmen in Westhoughton, Bolton.

  • Free, with no sign-up
  • 8% Judgments Act
  • County Court £5,000 rule
  • Payments on account
  • Nothing leaves your browser

Enter the order and the costs. The interest, what is outstanding and every period appear on the right.

The order for costs
As assessed or agreed, including VAT where it is payable. Work out the costs of the assessment separately: interest on them runs from the certificate.
When interest runs
Today by default

Leap years

The first divides a year of interest that contains 29 February by 366, following Lomas v Burlington [2015] EWHC 2269 (Ch); the figure by the other method shows if it differs.
The rate
Payments
Detailed assessment timing
More than 3 months after the right to costs and the court may disallow interest (CPR 47.8(3))

Interest on costs

Nothing yet

The interest builds here as you answer: the total due, the daily rate, and every period with its days, rate and payments.

Nothing you enter leaves your browser. Simple interest; the start day is not counted and the end day is. It is a guide, not legal advice.

The calculator applies the Judgments Act 1838, the County Courts Act 1984 s.74, the County Courts (Interest on Judgment Debts) Order 1991 as amended, and CPR Parts 36, 40, 44 and 47, checked on 19 October 2026. It does not cover contractual interest, judgments in a foreign currency, instalment orders or the family court, and it flags, but does not decide, the position where the Crown must pay. It is a guide, not legal advice.

Key points

  • An order for costs carries simple interest at 8% a year from the date of the order, even before the costs are assessed (Judgments Act 1838 s.17; Hunt v R M Douglas (Roofing) Ltd [1990] 1 AC 398; CPR 40.8).
  • Where a Part 36 offer is accepted within the relevant period after the claim was issued, interest on the costs runs from the date of acceptance (CPR 44.9(4)); an offer accepted before issue gives no deemed costs order (CPR 44.9(2)), so interest runs from an order in costs-only proceedings.
  • In the County Court only a judgment or order for £5,000 or more carries interest, unless the debt is a Late Payment Act qualifying debt; once it qualifies, interest runs on the unpaid balance until it is paid (County Courts (Interest on Judgment Debts) Order 1991, arts 1(2) and 2).
  • The court can order interest to run from an earlier or later date (CPR 40.8 and 44.2(6)(g)), but it cannot change the 8% rate (Horne v Prescot (No 1) Ltd [2019] EWHC 1322 (QB)). For a period before judgment interest starts, such as from when the costs were incurred, it can award interest at a rate it decides.
  • If detailed assessment is started more than 3 months after the right to costs arose, the court may disallow all or part of the interest (CPR 47.8(3)).
  • In the County Court payments go to the costs first (1991 Order art 6(2)); in the High Court no rule decides it for costs, so the calculator shows both ways.

How to use the interest on costs calculator

  1. Enter the order. The court, what gave the right to costs, the date of the order (or of acceptance), and the costs.
  2. Set the dates. Interest runs from the order unless the court ordered another date; calculate to today or another date.
  3. Set the rate. 8% under the Judgments Act, with any period at a rate the court set before judgment interest starts, or for enhanced interest, including Bank Rate plus a margin.
  4. Add any payments. Each payment on account or other payment, with its date, and in the High Court how payments are applied.
  5. Read the figures. The interest, what is outstanding, the daily rate now, and every period with its days, rate and payments.
  6. Copy them. Copy the figures and the period table for a letter, the bill or the file.

When interest on costs starts

Under the incipitur rule an order for costs is a judgment debt from the day it is made, so interest runs from then even though the amount is fixed later by agreement or assessment (Simcoe v Jacuzzi UK Group plc [2012] EWCA Civ 137). Where one bill covers orders with different dates, the interest has to be worked out for each.

Order or eventInterest runs fromAuthority
Order for costs to be assessed if not agreedThe date of the orderCPR 40.8; Hunt v R M Douglas
Order for costs of a stated sum (summary assessment)The date of the order; in the County Court, the date for payment where the order sets one (our reading)CPR 40.8; 1991 Order art 3(a)
Part 36 offer accepted within the relevant period, after the claim was issuedThe date of acceptanceCPR 44.9(4)
Part 36 offer accepted before the claim was issuedNo deemed order: the date of the order in costs-only proceedingsCPR 44.9(2); CPR 46.14
Part 36 offer accepted late, or less than 21 days before trialThe date of the court’s order on costsCPR 36.13(4) and (5)
Settlement approved by the court (child or protected party)The date of the approval orderCPR 21.10; CPR 36.14(4)
Claim discontinued (the defendant’s costs)The date the notice of discontinuance was servedCPR 38.5(1), 38.6; CPR 44.9(1)(c) and (4)
Costs of the detailed assessment proceedingsThe date of the default, interim or final costs certificateCPR 47.20(6)
The court ordered another dateThe date orderedCPR 40.8; CPR 44.2(6)(g)

The rate, and what the court can change

The judgment rate has been 8% a year since 1 April 1993 (S.I. 1993/564). It is set by the Secretary of State, and the court has no power to alter it (Horne v Prescot (No 1) Ltd [2019] EWHC 1322 (QB)). What the court can change is when interest runs: from or until a particular date, including a date before judgment (CPR 44.2(6)(g); CPR 40.8). For a period before judgment interest starts, such as from when the costs were incurred, the court can award interest at a rate it decides, often a margin over Bank Rate, and it can postpone judgment interest and set a rate until then: in Involnert Management Inc v Aprilgrange Ltd [2015] EWHC 2834 (Comm) the court ordered Base Rate plus 2% until three months after the orders for costs, and 8% after that (see also Secretary of State for Energy and Climate Change v Jones [2014] EWCA Civ 363). That is routine in commercial cases, but under a conditional fee agreement the client has usually paid little before the order beyond some disbursements. Enhanced interest on costs after a claimant’s Part 36 offer is beaten is ordered unless the court considers it unjust, at a rate it decides of up to 10% above Bank Rate (CPR 36.17(4)(c)). The calculator never suggests a rate: enter the periods the court ordered, with 8% from the date judgment interest starts.

The County Court: £5,000 and the exceptions

Under section 74 of the County Courts Act 1984 and the County Courts (Interest on Judgment Debts) Order 1991, as amended, a County Court judgment or order carries interest only if it is for £5,000 or more, or for a qualifying debt under the Late Payment of Commercial Debts (Interest) Act 1998. Interest then runs on the unpaid balance until it is paid. There is no interest on a judgment on a regulated consumer credit agreement, or on a suspended order for possession of a dwelling-house obtained by a landlord or a mortgagee; interest on an order payable by instalments runs only on an overdue instalment; and it stops when enforcement in the County Court produces a payment, or while an attachment of earnings or administration order is in force. Since 27 May 2019 the County Court can also order interest to run from another date. Where the Crown must pay, as the Ministry of Defence does in military hearing loss claims, section 24(1) of the Crown Proceedings Act 1947 applies section 17 of the Judgments Act 1838 to judgment debts due from the Crown, which arguably gives 8% on costs below £5,000 too, though section 24(2), on interest on costs, refers to costs awarded in the High Court. The calculator gives the 1991 Order answer and shows the section 17 figure beside it; and because no execution runs against the Crown (section 25(4)), the enforcement stops do not apply.

Payments on account

In the County Court a payment is applied to the principal first and then to the interest (1991 Order art 6(2)). In the High Court no rule decides how a part payment is applied to interest on costs. Costs practice deducts payments on account from the costs; the Court of Appeal has approved applying part payments to interest first as a rule of thumb (Evonik UK Holdings Ltd v HMRC [2025] EWCA Civ 1392). An agreement between the parties, or what the payer said the payment was for, decides it. The calculator applies payments to the costs first and shows the figure the other way.

Daily interest and leap years

The calculator counts the days after the start date up to and including the end date, and divides the yearly interest by 365 without rounding the daily figure first (GOV.UK’s own example rounds it and so overstates the interest). In Lomas v Burlington Loan Management Ltd [2015] EWHC 2269 (Ch) the court held that a judgment creditor is entitled to 8% for each complete year whether or not it is a leap year, so a year of interest that contains 29 February is divided by 366. The calculator follows that by default and shows the 365-day figure beside it.

Starting detailed assessment late

Detailed assessment must be started within 3 months of the judgment, order or other event giving the right to costs (CPR 47.7). If it is started later, or the hearing is requested late, the court may disallow all or part of the interest otherwise payable (CPR 47.8(3) and 47.14(4)). Enter the date the notice of commencement was served to see the interest for the late period. Our detailed assessment deadline calculator gives the full timetable.

Sources

Frequently asked questions

8% a year, simple, under section 17 of the Judgments Act 1838 and the Judgment Debts (Rate of Interest) Order 1993. The court can change the date it runs from, but not the rate (Horne v Prescot (No 1) Ltd [2019] EWHC 1322 (QB)). Interest for a period before judgment interest starts, and enhanced interest after a claimant’s Part 36 offer is beaten, are at a rate the court decides. In the County Court the 8% applies to judgments and orders of £5,000 or more under the County Courts (Interest on Judgment Debts) Order 1991.
From the date of the order for costs, even where the costs are still to be assessed (Hunt v R M Douglas (Roofing) Ltd [1990] 1 AC 398; CPR 40.8). Where a Part 36 offer is accepted within the relevant period after the claim was issued, it runs from the date of acceptance (CPR 44.9(4)); there is no deemed costs order when an offer is accepted before issue (CPR 44.9(2)). Interest on the costs of the detailed assessment itself runs from the costs certificate (CPR 47.20(6)). The court can order another date.
Yes. An order for costs to be assessed if not agreed carries interest from the date of the order, not from the date the amount is fixed (Hunt v R M Douglas (Roofing) Ltd; Simcoe v Jacuzzi UK Group plc [2012] EWCA Civ 137).
Only if the judgment or order is for £5,000 or more, or the debt is a qualifying debt under the Late Payment of Commercial Debts (Interest) Act 1998 (1991 Order arts 1(2) and 2). A costs order on its own, such as the deemed order when a Part 36 offer is accepted, needs costs of £5,000 or more; where the same judgment also orders damages, the usual commentary view adds them together. Some orders carry no interest, such as those under a regulated consumer credit agreement, and interest stops when enforcement in the County Court produces a payment. Where the Crown must pay the costs, section 24(1) of the Crown Proceedings Act 1947 arguably gives 8% whatever the amount, though the point is not settled.
In the County Court a payment goes first to the costs and then to the interest (1991 Order art 6(2)). In the High Court no rule decides it for interest on costs: usual practice deducts payments on account from the costs, while the Court of Appeal has approved applying a part payment to interest first as a rule of thumb (Evonik UK Holdings Ltd v HMRC [2025] EWCA Civ 1392). The calculator applies payments to the costs first and shows the other figure.
Costs times 8% divided by 365, without rounding the daily figure before multiplying. For a year of interest that contains 29 February, the calculator divides by 366, following Lomas v Burlington Loan Management Ltd [2015] EWHC 2269 (Ch), so that a full year earns exactly 8%; it shows the figure using 365 every year beside it.
Yes. If the receiving party starts detailed assessment more than 3 months after the right to costs arose, or requests the assessment hearing late, the court may disallow all or part of the interest (CPR 47.8(3) and 47.14(4)). The calculator shows the interest for the late period when you enter the date the notice of commencement was served.
No. Judgment interest is simple interest: unpaid interest does not itself earn interest.

Costs to recover, with the interest?

We work for claimant solicitor firms: we prepare the bill of costs, deal with the Points of Dispute and negotiate the costs, with the interest, to settlement. The fee is fixed and agreed before any work begins.

Request a fixed-fee quote →More free tools