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Index Rent Calculator 2026

How much may your German index-linked rent rise? Calculate the new rent with the official monthly consumer price index, when it applies, and whether your landlord's increase is correct.

100% freeNo data storedCPI up to August 2026

Not legal advice

The calculator follows § 557b of the German Civil Code (BGB) using the official CPI values (base 2020 = 100). It does not check whether your index rent clause is valid or which index months your lease specifies. In a dispute, a tenants' association, a landlords' association or a tenancy lawyer can help.

What would you like to do?

Rent & index

€

Index value: 122.3

Index value: 125.8

Deadlines

New net rent (cold)

€822.89

per month · Before: €800.00 · Change: +2.86 %

Extra per month

€22.89

Extra per year

€274.68

Old index value

122.3

August 2025

New index value

125.8

August 2026

Index change

+2.86 %

+3.5 points

Payable at the earliest from

1 November 2026

Month after next following receipt (September 24, 2026)

November 2026

One year after the last change

October 2026

Receipt sets the date: the changed rent is payable from the start of the month after next following receipt of the declaration (§ 557b(3) BGB).

For the adjustment to apply as early as possible, the declaration must be received by August 31, 2026 at the latest.

Consumer price index and your rent

Monthly values from the Federal Statistical Office. Marked: old and new index month. There are 12 months between the index months.

Annual inflation for comparison

Change of the CPI annual averages on the previous year; 2026 provisional (January to August).

Calculation

New rent = current rent × new index ÷ old index

Current rent€800.00
New index value ÷ Old index value125.8 ÷ 122.3
Factor1.02862
New rent€822.89

Checklist for the letter (§ 557b(3) BGB)

  • Text form: a letter, email or fax naming the landlord is enough; no signature is required (§ 126b BGB).
  • The change in the price index must be stated, i.e. the old and new index values.
  • The new rent or the increase must be stated as an amount in euros.
  • Both index values must use the same base year (currently 2020 = 100).
  • At least one year must have passed since the last rent change. Modernisation and service-charge adjustments do not count.
  • During an index rent, no increase to the local comparative rent (§ 558 BGB) is possible.

Good to know

  • No cap: the 20% or 15% limit (Kappungsgrenze) in § 558(3) BGB only applies to increases up to the local comparative rent. Because § 557b(2) BGB excludes such increases during an index rent, index increases have no cap. The rent simply follows the index.
  • Rent brake: §§ 556d to 556g BGB only apply to the initial rent (§ 557b(4) BGB). Later index increases are not measured against it.
  • Modernisation: under an index rent, an increase under § 559 BGB is only possible if the landlord is not responsible for the measure, except for a modernisation under § 555b no. 1a BGB (heating system).
  • Net rent only: service charges are separate. Advance payments are adjusted after the annual statement (§ 560 BGB), not via the index.
  • The calculator uses the official monthly CPI for Germany (base 2020 = 100), as of 18 Sept 2026. Old values on base 2015 or 2010 must be converted. Never compare values on different bases.

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Guide: Index Rent in Germany

Formula, deadlines, landlord letters, rent brake and the consumer price index

Index Rent in Germany 2026: Formula, Deadlines and Your RightsFeatured

Index Rent in Germany 2026: Formula, Deadlines and Your Rights

The complete guide to index rent under § 557b BGB: how the new rent is calculated, when it applies, why there is no cap, and the mistakes landlords often make.

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Checking an Index Rent Increase: The 6 Key Points

Checking an Index Rent Increase: The 6 Key Points

A letter from your landlord with a new index rent? How to check form, index values, amount and date, and how to respond if something is wrong.

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Index Rent or Graduated Rent? A Comparison for Tenants and Landlords

Index Rent or Graduated Rent? A Comparison for Tenants and Landlords

Both models fix future rent increases in the lease, but with very different risks. Differences, a worked example and which suits whom.

2026-09-245 min read
Index Rent and the Rent Brake: What Applies to the Initial Rent

Index Rent and the Rent Brake: What Applies to the Initial Rent

With an index rent, the rent brake only applies to the initial rent. What that means, how to challenge an excessive starting rent and why later increases are not capped.

2026-09-245 min read
The Consumer Price Index Explained: Base Year, Monthly Values, Rebasing

The Consumer Price Index Explained: Base Year, Monthly Values, Rebasing

Which index applies to index rent, where to find the monthly values, what 2020 = 100 means and how to convert old values to a new base.

2026-09-245 min read

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Frequently Asked Questions

The rent changes in the same proportion as the consumer price index: new rent = current rent × new index ÷ old index. Example: €800 net rent, index rose from 110.0 to 115.5. 115.5 ÷ 110.0 = 1.05, so the new rent is €840. What matters is the percentage change, not the difference in index points. The calculator above fills in the official monthly values automatically.

From the start of the month after next following receipt of the declaration (§ 557b(3) BGB). If the letter arrives on 24 September, the new rent applies from 1 November. In addition, the rent must have remained unchanged for at least one year since the last change (§ 557b(2) BGB). The later of the two dates applies. There is no retroactive increase.

No. The cap of 20% or 15% within three years is in § 558(3) BGB and only applies to increases up to the local comparative rent. Such increases are excluded during an index rent (§ 557b(2) BGB). An index rent therefore follows the consumer price index alone, even when inflation is high, as in 2022 and 2023. The only outer limit is the rule against excessive rents (§ 5 of the Economic Offences Act, WiStG).

Text form under § 126b BGB: a letter, email or fax that shows who is making the declaration. No signature is required. The letter must state the change in the price index and the new rent or the increase in euros. The increase does not happen automatically. As long as the landlord makes no declaration, the current rent remains.

Yes. The index rent is determined by the index, in both directions. If the consumer price index falls compared with the level at the last adjustment, tenants can demand a reduction by a declaration in text form. The one-year rule and the "month after next following receipt" date also apply then. In practice this is rare, because the index has risen almost continuously since 2015.

The law does not prescribe specific months. Common practice compares the index level at the time of the last adjustment (or start of the lease) with the latest value published before the declaration. Some leases name fixed months. Important: both values must use the same base, currently 2020 = 100. If the landlord takes the old level from a month before the last adjustment, the increase comes out too high, because part of the rise is counted twice.

Only for the initial rent (§ 557b(4) BGB). In areas with a rent brake, the rent at the start of the lease may be at most 10% above the local comparative rent, with exceptions such as a higher previous rent. Later index increases are no longer measured against the rent brake. Graduated rent is different: there the rent brake applies to every step.

Only to a limited extent. Under § 557b(2) BGB, a modernisation increase (§ 559 or § 559e BGB) is only possible insofar as the landlord carried out the building work due to circumstances beyond their control, such as legal obligations. Exception: modernisations under § 555b no. 1a BGB (heating system). Service charges are adjusted separately under § 560 BGB.