Invoice Late Fee Calculator

Late fees turn 'I'll get to it' into 'I'll pay it now'

A late-payment fee that is written into your terms and actually applied changes client behaviour. It signals that your time and cash flow have a price. This calculator works out the interest owed from the outstanding amount, the number of days overdue, and your stated rate.

Choose a flat fee for a simple penalty, simple interest for a daily charge on the original amount, or compounding for longer overdue periods. Always set the expectation in your contract and on the invoice before you apply it.

What rate can I charge?

Common practice is 1–2% per month, or a statutory rate where one applies. Many jurisdictions set a legal maximum and some give small businesses a statutory right to interest plus a fixed recovery fee on late commercial payments. Check the rules where you and your client operate, and keep your rate reasonable and disclosed.