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Late Payment Interest Calculator

Calculate late payment interest per Section 288 BGB for consumers and businesses. Automatic period splitting upon base rate changes, with full calculation steps and sub-period table.

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Optional: Overrides the statutory rate

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For illustration only – your own calculation is what counts.

Explanation

How Late Payment Interest Calculator works

Late payment interest under German law

Late payment interest in German law

Anyone who fails to pay a due monetary claim on time is in default and owes the creditor late payment interest. These are regulated in Section 288 BGB and serve as lump-sum damages — the creditor does not need to prove actual damage.

Knowledge

Legal basis (Section 288 BGB)

Late payment interest is regulated in Section 288 BGB and amounts to 5 percentage points above the base rate for consumers and 9 for businesses.

Section 288 BGB regulates the level of late payment interest. A monetary debt bears interest during default. The default rate is five percentage points above the base rate per year (Para. 1). For transactions not involving a consumer, the rate is nine percentage points above the base rate (Para. 2).

The creditor can also claim higher damages (Section 288 Para. 4 BGB). Statutory late payment interest represents only the minimum damage.

Knowledge

Base interest rate (Section 247 BGB)

The base interest rate is recalculated semi-annually by the Deutsche Bundesbank and serves as a reference for many statutory interest rates.

The base interest rate per Section 247 BGB is recalculated by the Deutsche Bundesbank on January 1 and July 1 respectively. It changes by the percentage points by which the reference figure (ECB main refinancing rate) has risen or fallen since the last change of the base rate.

Historically, the base rate was in negative territory between 2016 and 2022 (approx. -0.88%). Since mid-2022, it has risen significantly again due to ECB rate increases.

Knowledge

Calculation method

Late payment interest is calculated on a day-exact basis and split into sub-periods upon base rate changes.

Basic formulaLate payment interest = Claim amount × Default interest rate × Days / Days in year

The default interest rate is made up of the base rate + surcharge (5 or 9 percentage points). Under ACT/ACT the days in the year are 365, or 366 in a leap year.

When the base rate changes during the default period, the calculation is split into sections. The respective base rate applies for each section. Total late payment interest is the sum of all sub-amounts.

Day counting uses the ACT/ACT method (actual days relative to actual days in the year). This is the standard method for late payment interest in Germany.

Practice

Practical examples

For illustration only – your own calculation is what counts.

Consumer in payment default

A consumer owes EUR 5,000 from an invoice. Default runs from 01.03.2024 to 30.06.2024. The statutory base rate plus 5 percentage points applies.

Result: The calculator loads the base rate valid for the default period from the reference data source, adds the 5 percentage points for consumers and shows the default interest rate, the interest days (ACT/ACT) and the total in the result.

Business-to-business (B2B)

A company owes a supplier EUR 12,000. Default runs from 15.01.2024 to 15.07.2024. In B2B transactions, a surcharge of 9 percentage points applies.

Result: The period extends beyond the half-year change on 1 July. The calculator therefore splits it into two sub-periods with the respective valid base rate, adds the 9 percentage points for business transactions and sums the sub-amounts into the total.

Fixed contractual rate

A loan agreement provides for a fixed default rate of 12% p.a. The outstanding claim is EUR 8,000, default runs from 01.04.2024 to 01.10.2024.

Result: At a fixed contractual rate of 12% p.a. and 183 interest days (ACT/ACT, leap year 2024), late payment interest amounts to exactly EUR 480.00 (EUR 8,000 × 12% × 183/366). The statutory base rate is not used.

Base rate change during default

A claim of EUR 10,000 has been due since 01.05.2024. Default ends on 28.02.2025. During this period, the base rate changes on 01.07.2024 and 01.01.2025.

Result: The calculation is split into three sub-periods (01.05-30.06.2024, 01.07-31.12.2024, 01.01-28.02.2025). For each section the calculator loads the base rate then valid from the reference data source, adds the 5 percentage points and sums the sub-amounts into the total default interest.

Notes

Common mistakes

  1. Setting the wrong start of default

    Default does not begin automatically at maturity but only after a formal demand or after 30 days from invoice receipt (for consumers only with notice). Calculating from the maturity date may overcount interest days.

    Correctly determine start of default: Day after formal demand or after expiry of the 30-day period.

  2. Confusing consumer and business rates

    Consumer: Base rate + 5 percentage points. Business (B2B): Base rate + 9 percentage points. The mix-up results in a difference of 4 percentage points — for EUR 10,000 and one year, approx. EUR 400 difference.

    Correctly determine debtor type: Consumer = +5 percentage points, B2B transaction = +9 percentage points.

  3. Not updating the base rate

    The base rate changes semi-annually. For longer default periods, the applicable base rate per half-year must be used. An outdated base rate leads to incorrect results.

    For cross-period defaults, check the base rate per half-year and split the calculation.

FAQ

Frequently asked questions

What is late payment interest?

Late payment interest is the statutory compensation a debtor must pay when they fail to settle a due monetary claim on time. It compensates the creditor for not having the owed money available in time. The legal basis is Section 288 BGB. Late payment interest becomes due automatically without the creditor needing to prove actual damage.

How do late payment rates differ for consumers and businesses?

The law distinguishes two cases (Section 288 Para. 1 and 2 BGB): Consumer: Base rate + 5 percentage points. Business (payment claims in commercial transactions): Base rate + 9 percentage points. The higher rate for businesses creates a stronger incentive to pay invoices promptly in commercial transactions.

What is the base interest rate and how often does it change?

The base interest rate is a reference rate determined by the Deutsche Bundesbank (Section 247 BGB). It is recalculated on January 1 and July 1 of each year and is based on the ECB's key interest rate. Since the base rate can change semi-annually, calculations for longer default periods must be split into sub-periods.

When does default begin (Section 286 BGB)?

Default typically occurs when: The debtor has been formally demanded payment after maturity (Section 286 Para. 1 BGB); 30 days have passed after maturity and receipt of an invoice (Section 286 Para. 3 BGB); a calendar-specific payment date has passed (Section 286 Para. 2 No. 1 BGB); the debtor has seriously and finally refused payment (Section 286 Para. 2 No. 3 BGB). For consumers, the invoice must contain a notice about default occurring after 30 days.

Why is the calculation split into sub-periods?

Since the base rate can change on January 1 and July 1, the calculation must be divided into sections for cross-period defaults. The respective base rate applies for each section. Example: For default from 01.05.2024 to 31.01.2025, three sub-periods with potentially different base rates result (1st half 2024, 2nd half 2024, 1st half 2025).

Can higher damages be claimed?

Yes. Per Section 288 Para. 4 BGB, the creditor can also claim higher damages if they can prove them. Statutory late payment interest represents only the minimum damage. Example: If the creditor had to take out a more expensive loan due to the missing money.

Does late payment interest also apply to partial payments?

Yes. If the debtor pays only part of the claim, late payment interest continues on the remaining open amount. The calculation must then be adjusted for the remaining amount from the partial payment date.

What is the EUR 40 collection flat rate?

In addition to late payment interest, the creditor has a right to a flat rate of EUR 40 for payment claims in commercial transactions (Section 288 Para. 5 BGB). This serves as lump-sum compensation for collection costs and is credited against actual damages.

Limits

Limitations

  • Base rate must be current: After a new publication by the Bundesbank, an update may be required.
  • No collection or recovery costs: Collection costs, attorney fees, and the EUR 40 flat rate (Section 288 Para. 5 BGB) are not calculated.
  • No substitute for legal advice: Whether default actually exists and what rights apply requires case-by-case legal assessment.
  • No partial payments modeled: For partial payments during default, the calculation must be manually split.

Sources

Sources and references

  • § 286 BGB — Verzug des SchuldnersBundesministerium der Justiz

    Legal regulation of the prerequisites for debtor default (formal demand, 30-day rule, calendar date).

    View sourceRetrieved: 07/30/2026 · Verified on: 07/30/2026 · Primary source
  • § 288 BGB — Verzugszinsen und sonstiger VerzugsschadenBundesministerium der Justiz

    Central legal basis for the level of late payment interest: Base rate + 5 percentage points (consumer) or + 9 percentage points (business).

    View sourceRetrieved: 07/30/2026 · Verified on: 07/30/2026 · Primary source
  • § 247 BGB — BasiszinssatzBundesministerium der Justiz

    Regulation for the calculation and semi-annual adjustment of the base interest rate by the Deutsche Bundesbank.

    View sourceRetrieved: 07/30/2026 · Verified on: 07/30/2026 · Primary source
  • Deutsche Bundesbank — Aktuelle BasiszinssätzeDeutsche Bundesbank

    Current and historical base interest rates of the Deutsche Bundesbank per Section 247 BGB.

    View sourceRetrieved: 07/30/2026 · Verified on: 07/30/2026 · Primary source