UK late payment interest on Stripe invoices: how to calculate and claim it

A business client paid your Stripe invoice two months late, or has not paid it yet. UK law lets you claim interest and a fixed sum for that. This guide covers what the law and GOV.UK say, how to work the numbers out, how to send the claim through Stripe, and a free calculator that does the arithmetic.

The short answer

For a late payment from another business, you can charge statutory interest of 8% plus the Bank of England base rate, and a fixed sum of £40, £70 or £100 depending on the size of the debt. GOV.UK says to send a new invoice if you decide to add interest. In Stripe that means a separate invoice that you create yourself.

What the rules say

When a payment is late. GOV.UK's page When a payment becomes late says an agreed payment date must usually be within 60 days for business transactions. If no date was agreed, the payment is late 30 days after the customer gets the invoice, or after you deliver the goods or service if that is later.
The rate. Interest on late commercial payments sets statutory interest at 8% plus the Bank of England base rate for business to business transactions, and says you cannot claim statutory interest if your contract sets a different rate of interest.
Which base rate. The Late Payment of Commercial Debts (Rate of Interest) (No. 3) Order 2002 uses the rate in force on 30 June for interest that starts to run between 1 July and 31 December, and the rate on 31 December for interest that starts between 1 January and 30 June. The Order extends to England and Wales and Northern Ireland. The Bank of England publishes the rate on its Bank Rate page.
From when. Under section 4 of the Act, statutory interest starts to run on the day after the relevant day, which is normally the agreed payment day.
The fixed sum. Section 5A and GOV.UK's page on debt recovery costs give £40 for a debt under £1,000, £70 from £1,000 to £9,999.99, and £100 from £10,000. You can charge it only once for each payment.

Working it out by hand

GOV.UK's own example uses a debt of £1,000 and a base rate of 0.5%: 8.5% a year is £85, which is 23p a day, so 50 days late comes to £11.50. For any invoice:

Add 8% to the base rate in force on the 30 June or 31 December before interest starts to run.
Multiply the amount by that rate and divide by 365.
Multiply by the days late, and add the fixed sum.

Claiming it through Stripe

An open Stripe invoice can show a Past due badge in the Dashboard, according to How invoicing works, and Stripe does not let you change most details of an invoice once it is finalised. So the claim goes on a new invoice. Following Stripe's Use the Dashboard:

Go to the Invoices page and click Create Invoice.
Select the existing customer.
Select Add one-time item and enter the interest, then another for the fixed sum, each with its quantity and price.
Use the Memo box to say which invoice the claim is for, the rate, the dates and the Act.
Choose a delivery option such as Email invoice with link, click Review invoice and send it.

Where this stops

The Stripe pages above cover past-due invoices and new invoices; the statutory amount is yours to work out, which means looking up a base rate, counting days and doing the sums for each claim.
It is easy to pick the wrong half-year rate, or to start counting on the due date instead of the day after.

The free calculator, and Duebill

Atesen Software's statutory interest calculator is free, needs no sign-up and stores nothing. Enter the invoice amount in pounds, the due date and the date it was paid (leave it empty for today). It shows the statutory rate with the base rate it used, the days late, the interest, the fixed-sum compensation and the total, with a line of working you can copy into a memo.

The calculator belongs to Duebill, a web app for UK businesses that invoice through Stripe. Once open, Duebill is designed to read your overdue and late-paid Stripe invoices every morning with a restricted key, calculate the interest and fixed sum, and list each claim with its working. When you approve a claim, Stripe sends it as a separate, itemised invoice; your original invoices are never changed. It covers GBP invoices to UK business clients only. It is not a Stripe App and is not listed in the Stripe App Marketplace.

Status. Duebill itself is not open yet: its site takes waiting list sign-ups, so no one can connect a Stripe account or buy a plan today. The calculator works today. Checkout is not open yet; the planned plans are Starter at $19 a month and Pro at $39 a month, each with a 14-day trial, with checkout by Paddle.

About Duebill Open the free calculator

Which route fits

One late invoice: work it out with the calculator or by hand, and send a new invoice from the Stripe Dashboard.
A contract with its own late payment rate: use that rate, not the statutory one.
Many late clients every month: a tool that finds them and drafts claims for you to approve.

Atesen Software is independent, and this page is not legal advice. Stripe is a trademark of Stripe, Inc., and this page is not affiliated with, sponsored or endorsed by Stripe. GOV.UK, legislation.gov.uk, Bank of England and Stripe pages were checked on 17 October 2026; rates and menus can change.

Questions about this guide: support@atesensoftware.com.