Enter the unpaid invoice amount, the annual interest rate you are entitled to charge, and the number of days the payment is overdue. The calculator shows the daily interest, the interest accrued so far, and the new total due.
How late-payment interest works
- The daily rate
- Annual interest is spread across the year: daily interest = amount x (annual rate / 100) / 365.
- The interest owed
- Multiply the daily interest by the number of days overdue. Interest usually runs from the day after the due date until payment.
- The EU statutory rate
- For commercial transactions in the EU, the Late Payment Directive (2011/7/EU) sets the statutory rate at the ECB reference rate plus at least 8 percentage points, on top of a fixed recovery fee. Your contract or national law may set a different rate.
Late payment interest FAQ
How is late payment interest calculated?
Take the overdue amount, apply the annual rate to get a yearly figure, divide by 365 for a daily figure, then multiply by the days overdue. The calculator does this as you type.
What interest rate can I charge on a late invoice?
It depends on your contract and local law. In the EU, business-to-business transactions carry a statutory right to interest at the ECB reference rate plus at least 8 percentage points, plus a fixed recovery fee, unless your contract sets a fair alternative.
When does interest start running?
Usually the day after the payment due date, and it continues until the invoice is paid in full. Count the calendar days the payment is late.
Can I add a fixed late fee as well?
Often yes. Many jurisdictions, including the EU, allow a fixed compensation amount for recovery costs in addition to interest. Check the rules that apply to you.