Thuringia Commercial Rent Increases: Index Clauses and Stepped Rent

Commercial rent in Germany — and in Thuringia — is not subject to the statutory Kappungsgrenze or Mietpreisbremse that restrict residential rent increases. 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.

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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.

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 — Price Clause Act (PrKG)

Pure-sliding index clauses in commercial leases are only valid under the Price Clause Act (Preisklauselgesetz) when:

• The lease term is at least 10 years (fixed or with tenant renewal options totalling 10 years), or
• The clause qualifies as a performance reservation (Leistungsvorbehalt) — e.g., either party has the right to re-negotiate the rent in light of the VPI shift, rather than it adjusting automatically.

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 writing with the new calculated rent.
3. 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

Under § 559 BGB, residential landlords may add a modernisation surcharge. 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
• 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. 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.

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