Late payment interest calculator

Estimate statutory interest and fixed recovery fees for overdue invoices using a practical UK-friendly workflow.

Rules last checked: . Primary source: GOV.UK.

Enter the overdue invoice details

Amount owed

Calculation basis

Invoice due date

Payment date

Bank of England base rate (%) This is prefilled from the last checked rate file and can be edited if the official base rate has changed.

What this calculator includes

Simple daily interest estimate.
Commercial debt recovery fee thresholds.
A separate court-claim style option with no fixed fee.

Before you send a demand

Confirm the invoice due date, confirm whether the debt is commercial, and make sure the rate used matches the official position for the period you are claiming.

Questions people ask

Does this replace a legal demand letter?

No. It is a calculation aid only. You still need to check the contract, the debt type, and the official guidance before sending a formal claim.

Why can the base rate be edited?

The Bank of England base rate can change. The calculator is prefilled from the site data file, but you can override it if you are checking a different period.