Invoice Late Fee Calculator
Enter the invoice amount, days overdue, and interest rate to see how much late payment interest is owed.
Chasing a UK business? The law lets you claim statutory interest and fixed compensation, and you can download a chasing letter and a PDF report with your own logo: use the full UK Late Payment Calculator. Chasing a US customer? Use the US Late Fee Calculator and Demand Letters to work out fees from your own terms and write a reminder, second notice or final demand.
Simple interest: invoice amount x rate x (days / 365).
late fee after 30 days at 6% per year
This is a rough figure. In the US, late fees and interest depend on what you agreed with your customer and on state law, so there is no one rate. Use your own terms, and write the letters, with the US Late Fee Calculator and Demand Letters.
Ok, a client owes me $5,000 and they're 30 days late. I'm not letting that slide, so what interest can I charge? The rate is 6% a year.
A whole year would be about $300, but they've only been late for 30 days out of 365.
So I'm owed $24.66 in interest, which makes the total $5,024.66.
If they take another 30 days, that's $49.32 in interest.
That's 0.49% on top. Small, but it makes the point.
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This tool calculates the late payment interest on an overdue invoice using simple annual interest, with preset rates for common jurisdictions.
How we work it out
We use simple interest: invoice amount multiplied by the annual rate divided by 100, multiplied by days overdue divided by 365. This matches the standard calculation used by most late payment legislation and business contracts.
Common mistakes
- Charging a late fee that was never in your terms. Check what you agreed first.
- Counting the days from the invoice date when interest runs from the due date.
- Sending the demand without the invoice number, the amount and the date it was due.
- Waiting too long to chase. The sooner you ask, the easier it is.
Questions
What is the UK statutory rate?
The Late Payment of Commercial Debts Act 1998 sets the statutory rate at 8 percentage points above the Bank of England base rate for business-to-business transactions. The base rate changes periodically, so the effective rate does too. The preset here is Bank Rate (3.75%) plus 8%, which is 11.75%. For an exact figure over several rate changes use the UK Late Payment Calculator.
Do I have to charge late fees?
No. Statutory late payment interest is a right you can exercise, not an obligation. Many businesses choose not to charge it to preserve the client relationship. That is your call.
Is this compound or simple interest?
Simple interest only. Compound interest would increase the figure further, but most late payment legislation and standard contract terms use simple interest.
Waiting on payment. At least the interest is ticking.