What default interest is
Anyone who pays a money claim late is in default (Verzug). For the period of default they owe interest on the open amount – default interest under Section 288 of the German Civil Code (BGB). It compensates the creditor for not having access to the money during that time.
For landlords this mainly matters for late rent and for unpaid service charge balances. The amounts are usually modest, but they belong in a clean statement of claim, for example for a reminder or a court payment order.
How to calculate default interest
The rate is made up of the base rate and a fixed surcharge. Interest is calculated to the day, without compound interest.
Default interest = amount owed × (base rate + surcharge) × interest days ÷ 365
- Surcharge of 5 percentage points if a consumer is involved – for example the tenant of a flat or you as a private landlord (Section 288 (1) BGB).
- Surcharge of 9 percentage points for payment claims where no consumer is involved – for example commercial rent where the landlord is also a business, such as a housing company (Section 288 (2) BGB). Whether private letting counts as acting as a consumer depends on its scale; with large portfolios it may be different.
- Interest days run from the day after the due date up to and including the payment date. If the base rate changes during the period, each section is calculated at its own rate.
- There is no interest on default interest (Section 289 BGB). The total is rounded to the cent once, at the end.
- If the debtor is not a consumer, a flat fee of €40 is added for payment claims (Section 288 (5) BGB) – even if you let privately. It is credited against later legal costs.
The base rate and its reset dates
The base rate (Basiszinssatz) is defined in Section 247 BGB. It changes on 1 January and 1 July; the Deutsche Bundesbank publishes the new value in the Federal Gazette. It can be negative: from 2020 to mid-2022 it stood at −0.88%, so default interest towards consumers was 4.12%.
Since 1 July 2026 the base rate has been 1.52%. If a consumer is involved, that means 6.52% default interest per year; if both creditor and debtor are businesses, 10.52%. The calculator takes the values from the table below and splits the period at every reset date.
Base rate and default interest rates since 2020
| Valid from | Base rate | Consumer involved (+5) | No consumer involved (+9) |
|---|---|---|---|
| 1 Jul 2026 | 1.52% | 6.52% | 10.52% |
| 1 Jan 2026 | 1.27% | 6.27% | 10.27% |
| 1 Jul 2025 | 1.27% | 6.27% | 10.27% |
| 1 Jan 2025 | 2.27% | 7.27% | 11.27% |
| 1 Jul 2024 | 3.37% | 8.37% | 12.37% |
| 1 Jan 2024 | 3.62% | 8.62% | 12.62% |
| 1 Jul 2023 | 3.12% | 8.12% | 12.12% |
| 1 Jan 2023 | 1.62% | 6.62% | 10.62% |
| 1 Jul 2022 | -0.88% | 4.12% | 8.12% |
| 1 Jan 2022 | -0.88% | 4.12% | 8.12% |
| 1 Jul 2021 | -0.88% | 4.12% | 8.12% |
| 1 Jan 2021 | -0.88% | 4.12% | 8.12% |
| 1 Jul 2020 | -0.88% | 4.12% | 8.12% |
| 1 Jan 2020 | -0.88% | 4.12% | 8.12% |
If part of the period falls after the latest published half-year, the calculator uses the last known rate and tells you so in the result.
Worked example: January rent arrives in March
A flat in Berlin, monthly rent €1,000. The rent for January 2026 only arrives on Friday, 6 March 2026.
- Find the due date: 1 January is New Year's Day, Friday 2 January is the 1st working day. Saturday and Sunday do not count, Monday 5 January is the 2nd and Tuesday 6 January the 3rd working day. Rent is due on 6 January.
- Count the interest days: from 7 January up to and including 6 March that is 25 + 28 + 6 = 59 days.
- Find the rate: base rate 1.27% (valid since 1 January 2026) plus 5 percentage points = 6.27% per year.
- Calculate: €1,000 × 6.27% × 59 ÷ 365 = €10.135, rounded €10.14.
In Bavaria the rent would only be due on 7 January, because 6 January is a public holiday there (Epiphany).
When a tenant is in default
Rent is payable at the start of the month, at the latest by the third working day (Section 556b (1) BGB). According to the case law of the Federal Court of Justice, Saturday does not count as a working day here; Sundays and public holidays in the state never do. For residential tenancies, that case law treats the payment as on time if the tenant instructs the bank transfer by the third working day.
Because the payment date is fixed by the calendar, the tenant is in default without a reminder (Section 286 (2) no. 1 BGB). A balance from the service charge statement is different: it needs a reminder, or default begins 30 days after the due date and receipt of the statement – towards consumers only if the statement specifically points out this consequence (Section 286 (3) BGB). In that case choose “Other claim” and enter the last day before default as the due date – with a reminder, the day it was received.
No fault, no default (Section 286 (4) BGB). And if the tenancy agreement sets a different due date, the agreement applies – the 3rd working day in the calculator is then only a suggestion.
Common mistakes
- Adding up several monthly rents and charging interest from one date. Each monthly rent has its own due date and therefore its own interest start.
- Counting Saturday as a working day and treating rent as late one day too early.
- Using an old base rate. It changes twice a year.
- Charging residential tenants 9 instead of 5 percentage points or asking for the €40 flat fee. And the other way round: charging 9 points as a private landlord of commercial space. The 9 points only apply if neither creditor nor debtor is a consumer.
- Adding interest to the claim and charging interest on it. Compound interest is excluded (Section 289 BGB).
Special cases: day count, part payments, limitation
The law does not say how to count days. A 365-day year is common; some divide by 366 in a leap year. In a leap year the difference is around 0.3% of the interest. You can switch the method under “More assumptions”.
If the debtor pays only part, the payment is applied first to costs, then to interest and finally to the principal (Section 367 (1) BGB). This calculator does not handle part payments. In that case calculate up to the payment date, deduct the payment first from the interest accrued by then, and from the following day charge interest only on the remaining principal.
Claims usually become time-barred after three years, counted from the end of the year in which they arose (Sections 195, 199 BGB). The calculator does not check this. For house money (Hausgeld) in an owners' association and for deposit instalments the calculation works the same way; only the due date follows from the resolution or Section 551 (2) BGB. For house money, 5 percentage points usually apply because owners are generally consumers.