The UK Late Payment Interest Calculator is a free web tool from UK Creative Ventures that works out the statutory interest and fixed compensation owed on an overdue business-to-business invoice under the Late Payment of Commercial Debts (Interest) Act 1998. You enter the invoice amount including VAT, the invoice date, your payment terms (or an agreed due date), and whether the invoice is still unpaid or was paid late; the calculator returns the interest owed, the fixed compensation charge, and a ready-to-send chasing email with your figures already filled in.
What is the UK Late Payment Interest Calculator?
The UK Late Payment Interest Calculator is a browser-based tool that computes statutory late payment interest and fixed compensation on overdue B2B invoices in England, Wales, Scotland and Northern Ireland. It takes the invoice amount, invoice date, payment terms or agreed due date, and payment status as inputs, and outputs a claim figure plus an editable chasing email. It is published by UK Creative Ventures, a Bristol-based agency.
Key Features
- Statutory interest calculation — applies 8% plus the Bank of England base rate on the correct reference date, currently 11.75% for invoices that became overdue in 2026.
- Automatic due date logic — uses your agreed payment terms, an agreed due date, or the 30-day default when no terms were agreed, counting from the later of invoice date and delivery.
- Fixed compensation — adds £40, £70 or £100 depending on the size of the invoice.
- Simple daily interest — accrues from the day after the due date up to the payment date, or to today if the invoice is still unpaid.
- Chasing email generator — writes a copy-ready email with your business name, customer name, invoice number and calculated figures inserted.
- Rate history table — lists the reference date, base rate and statutory rate for every half-year period back to 1 January 2019.
- Base rate override — lets you manually enter a Bank of England base rate for debts that became overdue before 2019 or for a period not covered by the table.
- Payment status options — handles both still-unpaid invoices and invoices that were paid late.
Who is it for?
- UK freelancers and contractors — chasing a business client who has blown past the agreed payment terms on a goods or services invoice.
- Small business owners and finance staff — quantifying exactly how much statutory interest and compensation can be added to an overdue B2B debt before sending a formal demand.
- Agency and studio accounts teams — producing a documented interest figure to support a letter before action or a small claims court claim.
- Businesses with no late payment clause — the statutory right applies automatically to B2B contracts, so no contract wording is needed.
What can you do with the UK Late Payment Interest Calculator?
- Quantify an overdue invoice: enter the amount, dates and terms to get the interest and compensation total you can legitimately claim.
- Draft a chasing email: generate pre-filled email text naming the customer, invoice number and figures, then edit and send it to the person who approves payments.
- Check the correct rate for an old debt: use the rate history table or the base rate override to find the statutory rate for invoices that became overdue in earlier half-year periods.
- Build evidence for escalation: keep a copy of the calculated claim to support a formal letter before action or a small claims court filing.
How does the calculator work?
It first establishes the due date from your agreed terms, an agreed due date, or the 30-day default. It then looks up the Bank of England base rate on the reference date for the half-year in which the invoice became overdue and adds 8%, fixing that rate for the whole life of the debt. Finally it calculates simple daily interest from the day after the due date and adds the fixed compensation band.
FAQ
Is the U
