Asset Management & Rental Potential

Calculating Rent Increases: Capping Limits, Local Indexes, and the Swiss Reference Interest Rate

Rent adjustments are bound to tight legal limits. Learn how to identify and execute rent potential lawfully across Germany, Switzerland, and Austria.

Updated July 9, 2026
Read time: approx. 12 mins
Over 1,600 words of expertise

Optimizing rent yield is a key task for any real estate asset manager. However, in the DACH region, tenancy laws protect tenants heavily. Landlords are restricted from arbitrary increases. This comprehensive guide outlines the rules governing rent increases in Germany, Austria, and Switzerland. We will explore capping limits, local rent indexes, modernization surcharges, and the Swiss benchmark interest rate mechanism.

1.Germany: Comparable Rents and Capping Limits

In Germany, § 558 BGB governs regular rent increases. The rent must remain unchanged for at least 15 months, and adjustments cannot exceed the **Comparable Rent Index (Mietspiegel)**. Additionally, a strict cap limit applies.

The Rent Cap (Kappungsgrenze)

Legally, rents cannot be raised by more than **20%** within a three-year period. In tight housing markets, regional authorities have lowered this cap to **15%** (e.g., Munich, Berlin).

2.Switzerland: The Benchmark Reference Interest Rate

Swiss tenancy law (Art. 269a OR) links rent to capital costs using a national **reference interest rate**. For every 0.25% increase, landlords may raise rents by up to **3.0%** (when rates are below 5.0%), plus minor adjustments for inflation (40% max CPI change) and maintenance costs.

Conclusion

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