Free UK business tool

Late payment interest calculator

Work out the statutory interest and fixed recovery sum you may be able to add to a qualifying overdue business invoice.

Uses 8% plus the current 3.75% Bank Rate
Includes the £40, £70, or £100 fixed recovery sum
No sign-up; figures stay in your browser

STATUTORY CALCULATION11.75% annual rate

Unpaid invoice amount

Payment was due

90 days overdue£2,539.53

Invoice: £2,400.00
Interest: £69.53
Fixed sum: £70.00

Interest continues at approximately £0.77 per day.

How the calculation works

What can be added to a late commercial payment?

11.75% a year

Statutory interest is 8% plus the Bank of England base rate. The calculator uses the current 3.75% reference rate.

£40–£100

The fixed recovery sum is £40 for debts below £1,000, £70 from £1,000 to below £10,000, and £100 from £10,000.

Daily until paid

Interest is calculated on the invoice amount for each overdue day. Contract terms and eligibility can change what applies.

Turn the number into action

Build the evidence trail and payment request.

Move your figures into Proofline’s free case builder, record your chases, and create a clear letter to send.

Build a free case file →

Check the official guidance. This calculator provides general information, not legal advice. Eligibility depends on your contract and circumstances.

GOV.UK: late commercial payments ↗