Thuringia Commercial Rent Increases: Index Clauses and Stepped Rent

Commercial rent in Germany — and in Thuringia — is primarily governed by the German Civil Code (Bürgerliches Gesetzbuch – BGB), which originally came into force on 1 January 1900. Following the Fourth Bureaucracy Relief Act (BEG IV) and the amended § 578 Abs. 1 BGB, commercial leases and any subsequent rent adjustment agreements no longer require the strict written form (§ 126 BGB). As of 1 January 2026, text form (§ 126b BGB), such as email or digital documents, is sufficient for all contracts.

Unlike residential tenancies, commercial leases are not subject to the statutory Kappungsgrenze or Mietpreisbremse. Instead, commercial rent is fixed by contract for the entire lease duration, unless the parties have contractually agreed a mechanism for future adjustments. If no adjustment mechanism is included in the lease, the rent cannot be unilaterally increased at all — a major risk for landlords in an inflationary environment.

Legal DisclaimerThis guide provides general legal information. Lease laws can change. Always consult a licensed notary or lawyer in this region.

Why Commercial Rent Clauses Are required

Unlike residential law (which provides a court-accessible pathway for landlords to align rent to market reference figures), there is no commercial equivalent of § 558 BGB. A commercial landlord locked into a long-term fixed rent (no index, no steps) signed before a significant inflationary period simply cannot raise the rent during the lease term — regardless of market changes. Furthermore, commercial index clauses are governed by the Price Clause Act (Preisklauselgesetz - PrKG), which establishes the statutory framework for such adjustments in business leases.

Including a rent adjustment mechanism at lease inception is therefore a fundamental commercial interest for every Thuringia commercial landlord.

1. Index Clauses (Wertsicherungsklausel / Gleitklausel)

The most widely used mechanism in long-term German commercial leases is tying the base rent to the official German Consumer Price Index (VPI) published monthly by the Federal Statistical Office (Destatis).

How It Works

When the VPI changes relative to the base index point (usually the index at lease inception), the rent changes proportionally. Many leases include a threshold trigger to avoid constant micro-adjustments — e.g., the clause only activates when the VPI has risen by 5% or 10% since the last adjustment.

Legal Requirement — PrKG & BGB § 307

Index clauses in commercial leases are governed by the Price Clause Act (Preisklauselgesetz) and General Terms and Conditions (GTC) law:

• Automatic Indexation (Gleitklausel): Valid only if the landlord waives the right to ordinary termination for at least 10 years, or the tenant has an option to extend the term to at least 10 years (PrKG § 3 Abs. 1 Nr. 1e).
• Performance Reservation (Leistungsvorbehalt): These are exempt from the 10-year requirement (PrKG § 1 Abs. 2 Nr. 1). However, the rent does not adjust automatically; instead, one party must have the right to demand an adjustment based on equitable discretion (§ 315 BGB).
• Symmetry Requirement: Following the Federal Court of Justice ruling (BGH XII ZR 51/25, March 11, 2026), all index clauses in standard contracts must be bilateral. A clause that only permits rent increases or treats decreases differently is void under § 307 BGB.

For leases shorter than 10 years, consult a specialist attorney in Thuringia before including an automatic sliding index clause.

Procedure for Adjustment

1. Landlord monitors VPI releases from Destatis.
2. When the threshold is reached, the landlord notifies the tenant in text form with the new calculated rent.
3. Under the symmetry requirement, the rent must adjust downwards if the index falls, just as it adjusts upwards.
4. The new rent is effective from the date stated in the notice — typically the start of the next full month.

2. Graduated Rent (Staffelmiete)

An alternative to index linking is graduated rent: the lease specifies the exact base rent amounts (in euros) at defined future dates or intervals. For example:

• Years 1–3: €15,000/month
• Years 4–6: €16,500/month
• Years 7–10: €18,000/month

This approach requires no monitoring or CPI tracking and is straightforward to administer. The trade-off is that graduation steps are fixed at signing and may significantly underperform or overperform relative to actual inflation.

The rent brake and residential Kappungsgrenze do not apply to the steps in Thuringia commercial graduated leases.

3. Modernisation Rent Surcharges

Unlike in residential law, there is no equivalent statutory provision in commercial tenancy law that automatically allows surcharges following capital improvements. Instead, commercial leases typically address this through:

• Negotiated lease variations at the time works are agreed (must be in text form)
• Pre-agreed rent adjustments in a lease annex tied to named improvement works

4. Rent Review on Lease Renewal

When a fixed-term commercial lease expires and is renewed, the parties renegotiate freely — the new rent is entirely market-driven with no statutory constraints. Any renewal agreement must be documented in text form. Many commercial leases include a renewal rent formula (e.g., "renewal rent to be the then-current market rent for comparable premises in the same location") to reduce renewal negotiation friction.

For indefinite commercial leases (Geschäftsräume), the statutory notice period is 6 months, with notice required by the 3rd working day of a calendar quarter to the end of the next calendar quarter (§ 580a Abs. 2 BGB).

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