What late payment really costs.
This calculator shows to the day how much late payment interest an overdue invoice accrues – with the current German base rate (Basiszinssatz), the right percentage points under § 288 BGB (German Civil Code) and the €40 flat fee that only applies to business clients.
Result
Total claim
€2,561.62
- Amount owed
- €2,500.00
- Late payment interest10.52% p.a. for 30 days · German base rate (Basiszinssatz) 1.52% + 9 percentage points
- €21.62
- Flat fee€40 per claim under § 288 (5) BGB
- €40.00
A calculation aid, not legal advice: whether and from when the debtor is in default depends on the contract, any dunning letter and the requirements of § 286 BGB (German Civil Code). The German base rate (Basiszinssatz) changes on January 1 and July 1.
Four inputs, and none of them is arbitrary.
The interest rate depends on who owes. For consumers it is the base rate plus five percentage points (§ 288 (1) BGB); for transactions without a consumer involved it is nine points (§ 288 (2) BGB). Using the same rate for both is the most common mistake in homemade dunning templates.
The base rate is not a fixed number. The Deutsche Bundesbank announces it anew under § 247 BGB on January 1 and July 1. A template that keeps an old rate quietly calculates wrong from the next cut-over date.
The €40 is not always due. The flat fee under § 288 (5) BGB applies per claim – but only if no consumer is involved. It does not belong in a dunning letter to private clients, and not a second time in follow-up letters for the same claim.
Default does not start automatically on the due date. When it starts is governed by § 286 BGB, and therefore by the contract, a dunning letter or a payment date fixed by the calendar. This calculator takes the date you enter – it does not make the legal assessment for you. The process is described on the page about writing a dunning letter.
In the end, the more interesting question is not what late payment costs, but why you have to send reminders at all. Usually because it was noticed too late that nothing came in.
Keep open receivables in view →From late payment interest to a finished dunning letter.
Sumaro calculates the late payment costs per claim itself and prepares the dunning letter as a draft – with a note on whether the client falls outside their usual payment pattern at all. Nothing is sent without your approval.