Index-Linked Commercial Rent: Does Your Clause Hold Up?
Index clauses and value-protection in commercial leases – what applies after the Federal Court of Justice’s judgment of March 2026
According to the Federal Statistical Office (Statistisches Bundesamt), the inflation rate in September 2026 was 3.3 per cent – the highest since December 2023. For many indexed commercial leases this leads to noticeable rent increases. Whether they are owed depends on the validity of the clause. In March 2026 the Federal Court of Justice (Bundesgerichtshof, BGH) clarified that such clauses are additionally subject to review under the law on standard business terms (AGB-Recht) – with considerable consequences.
What a Value-Protection Clause Is
A value-protection clause (Wertsicherungsklausel, also index clause) links the rent to a price index, in practice usually the consumer price index of the Federal Statistical Office. If the index rises, the rent rises. The special rule for residential leases (§ 557b BGB) does not, in principle, apply to commercial premises. What matters here are the Price Clause Act (Preisklauselgesetz, PrKG) and the law on standard business terms.
First Hurdle: The Price Clause Act
Under § 1 Abs. 1 PrKG, the amount of a monetary debt may in principle not be determined “directly and automatically” (unmittelbar und selbsttätig) by the price of other, non-comparable goods. For leases, § 3 Abs. 1 Nr. 1 Buchst. d and e PrKG permits a link to the consumer price index if the contract runs for at least ten years from conclusion, the landlord waives ordinary termination for at least ten years, or the tenant can extend the term to at least ten years. In addition, the clause must be sufficiently specific and must not place either party at an unreasonable disadvantage – for example where only an index increase is passed on but not a decrease, or where only one party can demand an adjustment (§ 2 PrKG).
If a clause infringes only the Price Clause Act, it becomes invalid – unless the contract provides otherwise – only upon a final judicial determination; until then its effects remain unaffected (§ 8 PrKG). Increases already paid can then in principle not be reclaimed.
Second Hurdle: Review Under the Law on Standard Business Terms
By judgment of 11 March 2026 (XII ZR 51/25), the BGH held that index clauses drafted in advance by the landlord are additionally subject to the content control of standard business terms (Allgemeine Geschäftsbedingungen, AGB) under § 307 BGB. In the case decided, the clause referred to an index level that lay more than two years before the start of the lease. The tenant would thus have borne price increases from the period before the start of the contract without receiving anything in return. It also remained contradictory whether the rent changes automatically or only upon written request. The BGH confirmed the lower court’s assessment that the clause was unreasonably disadvantageous and non-transparent. Individually negotiated clauses are not subject to this review.
The Consequence: Reclaiming Is Possible
The legal consequence is decisive. If a clause fails under § 307 BGB, it is invalid from the outset; § 8 PrKG then does not protect the landlord. The tenant can reclaim the increases paid, as far as the claims are not time-barred; the regular limitation period is three years. For landlords with many identical standard-form leases, this can result in a considerable repayment risk.
Checklist for Landlords and Tenants
Check the term: at least ten years fixed, or a corresponding waiver of termination or an extension right for the tenant?
Check the base index: does it refer to the conclusion of the contract or the start of the lease, and not to a much earlier month?
Check the mechanism: is it clearly regulated whether the adjustment takes place automatically or on request, and which value applies to later adjustments?
Check symmetry: does the clause also work in the tenant’s favour if the index falls?
Check origin: standard-form clause or individually negotiated?
Landlords: review existing contracts and contract templates and adapt them for new contracts.
Tenants: review increases of past years and, in case of doubt, pay new increases only under express reservation so that reclaiming remains possible.
Conclusion
Particularly when inflation is rising, it is worth taking a close look at the index clause: a standard-form clause that is unclear or one-sided may be invalid from the outset. Please do not hesitate to contact us if you have any questions.
Status: 17 October 2026
NIETZER Rechtsanwälte · Attorneys at Law (USA) · Heilbronn · www.unternehmensrecht.com
This article is for general information purposes and does not replace legal advice in an individual case.
