In short
With index-linked rent (Indexmiete), your basic rent follows the consumer price index of the Federal Statistical Office (Statistisches Bundesamt, Destatis) (Sec. 557b BGB). The landlord may only change it once it has remained unchanged for at least one year, and only in proportion to the new index figure compared with the old one. There is currently no upper limit. The landlord must declare the increase in text form, stating the change in the index and the new amount, and you pay it from the month after next following receipt.
Key points
- Basis: Sec. 557b BGB. The only yardstick is the consumer price index for Germany, currently with the base 2020 = 100.
- Formula: new rent = old rent × new index ÷ old index. Index points are not percentages.
- How often: the rent must remain unchanged for at least one year each time. An increase up to the comparative rent is excluded.
- Limits: no cap; the rent brake only applies to the starting rent. A cap is planned but not yet in force (as of 11/2026).
- You do not have to consent. You should still check every declaration, as mistakes are common.
Contents
- Calculating index-linked rent: formula and example
- What is index-linked rent?
- How much may index-linked rent rise?
- Planned cap for index-linked rents (as of 11/2026)
- When and how often may the landlord increase the rent?
- Checking an index-linked rent increase: the test
- When is index-linked rent invalid?
- Index-linked rent and other rent increases
- Can index-linked rent fall?
- Index-linked rent, graduated rent or comparative rent?
- CPI table: consumer price index for the last 24 months
- FAQ
Calculating index-linked rent: formula and example
The Federal Statistical Office updates index-linked amounts using a simple formula:
new rent = old rent × new index figure ÷ old index figure
The old index figure is the value for the month on which the last adjustment was based, and for the first increase the value at the start of the contract. The new index figure is the value the landlord now relies on.
Worked example (rent and dates fictitious, index figures real according to Destatis, base 2020 = 100):
| Step | Value |
|---|---|
| Basic rent since the last adjustment (applies since 1 December 2025) | €900.00 |
| Index figure of the last adjustment, September 2025 | 122.6 |
| New index figure, September 2026 | 126.6 |
| Change in the index in points | 4.0 points |
| Change in the index in percent: 126.6 ÷ 122.6 | 3.26% |
| New basic rent: €900 × 126.6 ÷ 122.6 | €929.36 |
| Increase per month | €29.36 |
| Declaration received on 20 October 2026, new rent payable from | 1 December 2026 |
Typical calculation error: The landlord equates the 4.0 index points with 4% and demands €936.00. That is €6.64 a month too much. Because the index is above 100, the percentage increase is always smaller than the difference in points.
What is index-linked rent?
Index-linked rent is an agreement in the tenancy agreement under which the rent is determined by the price index for the cost of living of all private households in Germany calculated by the Federal Statistical Office (Sec. 557b (1) BGB). This means the consumer price index for Germany (Verbraucherpreisindex, VPI). If consumer prices rise, the rent may rise. If they fall, it can fall.
The agreement must be made in writing (Sec. 557b (1) BGB). Alongside graduated rent, it is the only form in which tenants and landlords can set out future rent increases in the contract in advance (Sec. 557 (2) BGB).
How to recognise it in the contract: Look for terms such as "Indexmiete", "Wertsicherung" (value protection), "Verbraucherpreisindex" or "§ 557b BGB". A clause might read like this (example, not a model wording): "The rent changes in line with the development of the consumer price index for Germany calculated by the Federal Statistical Office. A change can be requested by declaration in text form one year after the last change in rent at the earliest."
Basic rent only: Indexation applies to the basic rent. Operating costs are adjusted separately under Sec. 560 BGB.
How much may index-linked rent rise?
As much as the index. There is currently no upper limit for the individual adjustment. The cap in Sec. 558 (3) BGB only applies to increases up to the local comparative rent, and precisely this increase is excluded with index-linked rent (Sec. 557b (2) sentence 3 BGB).
Rent brake: With index-linked rent, it only applies to the starting rent, i.e. the rent at the start of the contract (Sec. 557b (4) BGB). It does not limit the later index adjustments. The state ordinances on the rent brake must expire at the end of 31 December 2029 at the latest (Sec. 556d (2) BGB).
What this means in figures (rent fictitious, index figures from Destatis): A basic rent of €800, agreed at an index of 105.2 in January 2022, would result in a rent of €962.74 with the value for September 2026 (126.6). That is 20.34% more. A comparative rent could rise by no more than 20% in three years, and by no more than 15% in areas covered by a state ordinance (Sec. 558 (3) BGB). However, index-linked rent can also stagnate at times while the comparative rent rises.
Planned cap for index-linked rents (as of 11/2026)
Bill, as of 11/2026, not in force. The federal government adopted the draft of an act amending the law on residential and commercial tenancies and forwarded it to the Bundesrat (the chamber representing the federal states) on 1 May 2026 (Bundesrat printed paper 265/26). It has been before the Bundestag as printed paper 21/6807 since 1 July 2026 and has been referred to the committees, but it has not yet been adopted. Under the bill, for housing in tight housing markets designated by ordinance, an index increase of more than 3% in one year is only to count by half: half of the part above 3% is disregarded when calculating the new rent (Sec. 557b (4) BGB-E).
What this would mean (worked example on the bill, rent fictitious): From September 2021 (103.8) to September 2022 (112.7), the index rose by 8.57%. Today, a rent of €900 could therefore rise to €977.17. Under the bill, 3% would count in full and the remaining 5.57% by half, 5.79% in total, i.e. €952.08.
Until the act is promulgated and enters into force, Sec. 557b BGB applies in its current version. We will update this section as soon as the Bundestag has decided.
When and how often may the landlord increase the rent?
No more than once a year: The rent must remain unchanged for at least one year each time (Sec. 557b (2) sentence 1 BGB). Increases because of modernisation or operating costs are not counted. What matters is the period in which the rent has stayed the same.
Text form: The landlord must claim the change by declaration in text form (Sec. 557b (3) BGB). Text form means: a legible declaration on a durable medium with the name of the person making it (Sec. 126b BGB). A letter, fax or email is sufficient; a handwritten signature is not needed.
Content: The change in the price index that has occurred and the new rent or the increase as an amount of money must be stated (Sec. 557b (3) sentence 2 BGB).
When it is payable: You pay the new rent from the start of the month after next following receipt of the declaration (Sec. 557b (3) sentence 3 BGB). If it is received on 20 October, the new rent applies from 1 December. There is no retroactive increase.
No obligation to increase: The landlord does not have to adjust the rent. If they refrain for a few years, they can later increase it to the then current index, but not retroactively.
Threshold clauses: Some contracts provide that the rent is only adjusted once the index has changed by a certain amount, for example 5%. This threshold then also applies.
Checking an index-linked rent increase: the test
Go through the increase letter point by point. Every point you answer with no is a reason to ask questions or have the increase checked.
Common mistakes in the increase letter
| Mistake | Consequence | What you can do |
|---|---|---|
| Index points calculated as percentages | increase too high | recalculate the amount with the formula, object to the difference |
| Wrong old index figure (e.g. month of the notification instead of month of the last adjustment) | increase too high or too low | take the index month of the last increase from the old letter |
| Values from different base years mixed | calculation wrong | look up both values on the same base at Destatis |
| Less than one year since the last change | increase too early | check the date of the last change |
| Change in the index or new amount missing | declaration does not meet Sec. 557b (3) BGB | point out the missing information to the landlord |
| Increase demanded retroactively or from the next month | too early, only payable from the month after next | only pay from the correct month |
| Service charges indexed as well | impermissibly high | only accept an increase of the basic rent |
| Additional increase up to the comparative rent demanded | excluded (Sec. 557b (2) sentence 3 BGB) | refuse consent |
What to do about an incorrect increase?
Recalculate and object: Write to the landlord in text form stating which information is missing or which amount results from your calculation. Until the matter is clarified, pay the amount you consider correct.
Reclaiming rent paid in excess: If you have already paid an incorrectly calculated increase, you can reclaim the excess amount under the rules on unjust enrichment (Sec. 812 (1) BGB). The regular limitation period of three years applies (Sec. 195 BGB). It begins at the end of the year in which the claim arose and you became aware of the circumstances (Sec. 199 (1) BGB).
When is index-linked rent invalid?
Whether index-linked rent is valid depends on the agreement in the contract. Typical problems:
- No written agreement: Sec. 557b (1) BGB requires a written agreement.
- Wrong yardstick: Only the consumer price index for Germany is permitted. The Federal Statistical Office has not calculated an index for special household types since 2003.
- One-sided clause: A clause under which the rent can only rise but not fall deviates from Sec. 557b BGB to the tenant's disadvantage and is invalid to that extent (Sec. 557b (5) BGB). The Berlin Regional Court (Landgericht) held such a clause to be invalid (Berlin Regional Court, judgment of 20 June 2024, 67 S 83/24).
- Hidden or unclear clause: In standard form contracts, the rules on standard terms and conditions apply.
Consequence: If the index agreement is invalid, the tenancy agreement usually remains in place, and the general rules apply to increases, above all the increase up to the local comparative rent under Sec. 558 BGB. More on these rules in the guide Rent increase.
Index-linked rent and other rent increases
Comparative rent: excluded as long as the index-linked rent applies (Sec. 557b (2) sentence 3 BGB).
Modernisation: The landlord can only demand a modernisation increase under Sec. 559 or Sec. 559e BGB if they carried out building work because of circumstances for which they are not responsible, for example because of a statutory obligation. The exception is a modernisation under Sec. 555b no. 1a BGB, i.e. the installation or setting up of a heating system within the meaning of Sec. 42 of the Building Modernisation Act (Gebäudemodernisierungsgesetz) (Sec. 557b (2) sentence 2 BGB). A voluntary modernisation, such as a new bathroom, does not entitle the landlord to increase the rent with index-linked rent.
Operating costs: The landlord adjusts advance payments and flat rates under Sec. 560 BGB, independently of the index-linked rent.
Can index-linked rent fall?
Yes. The rent is tied to the index, in both directions. If the index falls, you can demand a reduction. Sec. 557b (3) BGB applies here too: you must declare the change in text form, stating the change in the index and the new amount, and the lower rent applies from the month after next. The rent does not fall by itself. In recent years, however, the index has risen when viewed over twelve months (see the CPI table).
Index-linked rent, graduated rent or comparative rent?
| Feature | Index-linked rent | Graduated rent | Comparative rent |
|---|---|---|---|
| Provision | Sec. 557b BGB | Sec. 557a BGB | Sec. 558 to 558e BGB |
| Basis | consumer price index | amounts in the contract | local comparative rent, e.g. rent index |
| How often | rent unchanged for at least one year each time | each step at least one year | request one year after the last increase at the earliest, rent unchanged for 15 months |
| Upper limit | none (cap planned) | none, except the rent brake | cap of 20% in three years, 15% with a state ordinance |
| Rent brake | starting rent only | for each step | applies to the rent at the start of the contract |
| Tenant's consent | not needed, a declaration is sufficient | not needed | needed (Sec. 558b BGB) |
| Modernisation increase | only in special cases | excluded | possible |
| Predictability for tenants | low, depends on inflation | high, amounts are fixed | medium |
Who is index-linked rent good for? When inflation is low, it rises more slowly than many comparative rents; when inflation is high, it rises much faster. Tenants bear the inflation risk, and landlords forgo increases up to the comparative rent and passing on the costs of voluntary modernisation. Before you sign a tenancy agreement with an index clause, it is worth having the clause looked at, for example with a contract review at a fixed price.
CPI table: consumer price index for the last 24 months
Consumer price index for Germany, base 2020 = 100. Source: Federal Statistical Office (Destatis), table "Consumer price index for Germany", as of 13 October 2026, read on 9 November 2026. We calculated the change on the same month of the previous year from the rounded index figures; it may differ from the officially published inflation rate by 0.1 percentage points.
| Month | CPI (2020 = 100) | Change on the same month of the previous year |
|---|---|---|
| Sep 2026 | 126.6 | +3.3% |
| Aug 2026 | 125.8 | +2.9% |
| Jul 2026 | 125.6 | +2.8% |
| Jun 2026 | 124.6 | +2.3% |
| May 2026 | 125.0 | +2.6% |
| Apr 2026 | 125.2 | +2.9% |
| Mar 2026 | 124.5 | +2.7% |
| Feb 2026 | 123.1 | +1.9% |
| Jan 2026 | 122.8 | +2.1% |
| Dec 2025 | 122.7 | +1.8% |
| Nov 2025 | 122.7 | +2.3% |
| Oct 2025 | 123.0 | +2.3% |
| Sep 2025 | 122.6 | +2.4% |
| Aug 2025 | 122.3 | +2.2% |
| Jul 2025 | 122.2 | +2.0% |
| Jun 2025 | 121.8 | +2.0% |
| May 2025 | 121.8 | +2.1% |
| Apr 2025 | 121.7 | +2.1% |
| Mar 2025 | 121.2 | +2.2% |
| Feb 2025 | 120.8 | +2.3% |
| Jan 2025 | 120.3 | +2.3% |
| Dec 2024 | 120.5 | +2.6% |
| Nov 2024 | 119.9 | +2.2% |
| Oct 2024 | 120.2 | +2.0% |
You can find older values and the latest month in each case in the Federal Statistical Office's GENESIS-Online database. When the index is switched to a new base year, all index figures change. In that case, calculate the old and new figures on the same base.
FAQ
By what percentage may index-linked rent rise?
By as much as the consumer price index has risen since the last adjustment. There is currently no fixed upper limit, and the cap for comparative rents does not apply. From September 2025 to September 2026, for example, it was 3.26%.
Is index-linked rent still allowed?
Yes. Sec. 557b BGB continues to permit index-linked rent. A cap for areas with a tight housing market is planned but not yet in force (bill, Bundestag printed paper 21/6807, as of 11/2026). Until then, existing index-linked tenancy agreements remain valid unchanged.
How much will index-linked rent rise in 2026?
That depends on the month of your last adjustment. If it was in September 2025, the value for September 2026 results in an increase of 3.26%. We do not make a forecast for the coming months; the index is published anew every month.
How often may the landlord increase index-linked rent?
The rent must remain unchanged for at least one year each time, so no more than one adjustment per year. Increases because of modernisation in special cases and adjustments of operating costs are not counted (Sec. 557b (2) BGB).
Do I have to consent to an index-linked rent increase?
No. The landlord's declaration in text form is sufficient, and the new rent applies from the month after next following receipt. But you only have to pay if the declaration is correct. Check it with the test above.
Does the rent brake apply to index-linked rent?
Only to the starting rent at the start of the contract (Sec. 557b (4) BGB). If it was too high in an area covered by the rent brake, you can object. The rent brake does not limit the later index adjustments.
Is index-linked rent bad for tenants?
That depends on inflation. When price rises are low, it often rises more slowly than the comparative rent, and passing on the costs of voluntary modernisation is excluded. When inflation is high, as in 2022, on the other hand, it rises quickly and without a cap.
Can the landlord also increase index-linked rent because of modernisation?
Only by way of exception: if they carried out the work because of circumstances for which they are not responsible, or when installing a heating system under Sec. 555b no. 1a BGB (Sec. 557b (2) sentence 2 BGB). The landlord cannot pass on the costs of a voluntary modernisation with index-linked rent.
About the author
Dr. Georg Schröder, LL.M.
Dr. Georg Schröder is a lawyer and writes the guides of Recht 24/7. He explains legal questions so that you can follow them without legal training, and he reviews every guide before it is published.
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