German default interest and late fee calculator
Work out to the day what an overdue invoice earns you: default interest under §288 BGB and the 40 EUR late payment fee you can charge business customers. When the delay runs across 1 January or 1 July the Basiszinssatz changes. This calculator splits the period at those dates and applies the rate that was actually in force in each stretch.
How the calculation works
- Against consumers, default interest is 5 percentage points above the Basiszinssatz (§288 paragraph 1 BGB). That is currently 6.52 percent.
- Against businesses it is 9 percentage points above the Basiszinssatz (§288 paragraph 2 BGB), provided no consumer is involved. That is currently 10.52 percent.
- The 40 EUR flat fee applies to business debtors only (§288 paragraph 5 BGB). It is credited against any legal costs you claim later.
- The Deutsche Bundesbank resets the Basiszinssatz on 1 January and 1 July. Since 1 July 2026 it stands at 1.52 percent.
- If your delay runs across one of those dates, the period is split and each stretch is charged at the rate that applied then.
- Interest is calculated to the day: amount times rate times days divided by 365. The due date itself does not count (§187 paragraph 1 BGB).
Common questions about default interest
How high is German default interest right now?
The Basiszinssatz has stood at 1.52 percent since 1 July 2026. That gives 6.52 percent against consumers (a 5 point surcharge) and 10.52 percent against businesses (a 9 point surcharge).
When can I charge the 40 EUR flat fee?
Only when your debtor is not a consumer and the claim is for payment of goods or services (§288 paragraph 5 BGB). It applies once per late payment, so instalments and part payments each trigger it. If you later claim legal costs, the fee is credited against them.
When is my customer actually in default?
Either from a payment date fixed by the calendar on your invoice, from your first reminder, or at the latest 30 days after the invoice reached them (§286 BGB). Against consumers the 30 day rule only applies if you pointed it out on the invoice.
How do I calculate when the Basiszinssatz changes mid-delay?
Each stretch is charged at the rate in force during that stretch. An invoice due on 1 June 2026 and paid on 1 August is 61 days late: 29 days up to 30 June at the old Basiszinssatz and 32 days from 1 July at the new one. This calculator does that split for you and shows it.
Can default interest be excluded by contract?
No. An agreement made in advance that excludes the claim to default interest is void (§288 paragraph 6 BGB). Whether you actually enforce the interest is still your decision.
Note
This calculator is general guidance and does not replace legal advice. Check the current Basiszinssatz with the Deutsche Bundesbank before enforcing interest. It does not cover special cases such as a contractually agreed different rate, part payments, or damages beyond the statutory interest.
Keep track of unpaid invoices
revoBill shows you which invoices are overdue and lets you write the reminder straight from the invoice.
Related reading
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