UK Late Payment Calculator

Calculate the statutory interest and penalties you're legally owed on overdue B2B invoices under UK law.

Based on the Late Payment of Commercial Debts (Interest) Act 1998

£
Enter an amount and days overdue to see your calculation.

How it's calculated

The Late Payment of Commercial Debts (Interest) Act 1998 gives businesses the right to charge interest and a fixed debt recovery cost on overdue B2B invoices.

Interest rate
Bank of England base rate (3.75%) + 8% = 11.75% per annum
Fixed penalties
Under £1,000: £40
£1,000–£9,999: £70
£10,000+: £100

These are your legal rights — not optional extras. Most freelancers never claim them.

Frequently asked questions

Related reading
Turn this into a demand letter — free generator
Fill in your invoice details and get a ready-to-send formal letter with these exact figures in it.
How much interest can you charge? — the full rules
The formula behind this calculator, when the clock starts, B2B vs B2C, and how to actually claim it.
Client not paying? What to do, step by step
The escalation path from polite chase to court — and the mistakes to avoid along the way.
How to chase late invoices — playbook
Day-by-day timeline used by professional accounts teams, adapted for freelancers.

Stop leaving money on the table

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