Indexmiete: How to Calculate a VPI Increase (2026)
Indexmiete: How to Calculate a VPI Increase
Old rent × (new CPI ÷ old CPI), and you must assert the increase in text form.
The rent must stay unchanged for at least a year between adjustments, and the declaration must state the index movement that occurred (§ 557b Abs. 2 and 3 BGB).
§ 557b Abs. 3 BGBIn 60 seconds
With an index rent the rent follows the Federal Statistical Office's consumer price index; the new rent is old rent × (new CPI ÷ old CPI).
The rent must stay unchanged for at least a year between adjustments (§ 557b Abs. 2 BGB).
You assert the increase in text form, stating the index movement that occurred and the new rent or the increase as a sum of money (§ 557b Abs. 3 BGB).
The changed rent falls due from the start of the second month following receipt; unlike § 558 BGB, the tenant's consent is not required.
The cap in § 558 Abs. 3 BGB does not apply to an index rent; limiting the increase to it anyway simply gives money away.
What the law says
A change of rent under an index agreement must be asserted by declaration in text form, stating the change in the price index that has occurred and the respective rent or the increase as a sum of money. The changed rent is payable from the start of the second month following receipt. Working translation; the German original is the binding text.
Index rent or an increase under the Mietspiegel?
| Feature | Index rent (§ 557b BGB) | Comparable rent (§ 558 BGB) |
|---|---|---|
| Justification | the Federal Statistical Office's CPI | the Mietspiegel or comparable flats |
| Cap | does not apply | 20%, tight markets 15% over 3 years |
| Frequency | at the earliest after 1 year | at the earliest after 15 months |
| Form | text form, index stated | text form, with reasons |
| Tenant's consent | not required | required (§ 558b BGB) |
The cap in § 558 Abs. 3 BGB does not apply here, and the Mietspiegel is irrelevant. During the term an additional increase under § 558 BGB is excluded.
Related: Agreeing a stepped or index rent and Increasing rent under § 558 BGB.
What it means for each side
- Check the declaration states the index movement at all.
- Check that a year has passed since the last change.
- Pay only from the second month after receipt.
- Make sure both index figures come from the same series.
- Take both index figures from the same, current series.
- Check the interval before declaring.
- State the old and new CPI figures and the sum of money in the declaration.
- Set the due date at the second month following receipt.
Common mistakes
Taking the old CPI from an outdated index series distorts the whole calculation. Both figures must come from the same series.
An increase before a year has passed since the last change does not hold.
If the declaration names only the new rent and not the index movement, it is ineffective.
The new rent runs from the second month, not the next one. And an index clause allowing only increases and excluding decreases is vulnerable.
What to do next
Establish the index figures: the old CPI from the contract or last adjustment, the new one from the same series.
Check the interval. Has a year passed since the last change?
Calculate: old rent × (new CPI ÷ old CPI).
Draft the declaration in text form with both figures, and set the due date at the second month following receipt.
Frequently asked questions
How do I calculate an Indexmiete increase?
The formula is: new rent = old rent × (new VPI / old VPI). The relevant figure is the Verbraucherpreisindex (consumer price index) of the Statistisches Bundesamt (Federal Statistical Office), base year 2020 = 100. Example: a starting rent of 800 EUR at VPI 109.8 (old) and VPI 125.2 (new) gives 800 × (125.2 / 109.8) = 912.20 EUR. The legal basis is § 557b Abs. 1 BGB.
How often can an Indexmiete be increased?
At most once a year. Under § 557b Abs. 2 BGB the rent must stay unchanged for at least one year between adjustments. The period runs from the last rent change, not from the start of the tenancy.
Do the Kappungsgrenze or the Mietspiegel apply to an Indexmiete?
No. With an Indexmiete under § 557b BGB neither the Kappungsgrenze (the cap on rent increases, § 558 Abs. 3 BGB) nor the Mietspiegel (the official local rent index) applies. An increase under § 558 BGB is expressly excluded during an Indexmiete (§ 557b Abs. 2 BGB). The increase is limited only by the movement of the VPI.
From when must the tenant pay the higher Indexmiete?
From the start of the second month after the declaration is received (§ 557b Abs. 3 BGB). If the declaration arrives in March, the new rent is due from 1 May. The increase does not apply retroactively.
What form must the Indexmiete increase take?
Textform is sufficient (§ 557b Abs. 3 BGB). A letter or an email is enough, a signature is not strictly required. The declaration must state the change in the price index that has occurred and either the respective rent or the increase as a monetary amount.
Does the Mietpreisbremse apply to an Indexmiete?
The Mietpreisbremse (rent brake, §§ 556d–556g BGB) applies to an Indexmiete only for the starting rent at the beginning of the tenancy (§ 557b Abs. 4 BGB). The later index-driven adjustments are not capped by the Mietpreisbremse.
This page gives general information as at the date shown. It does not replace legal advice on an individual case.