Rent Increase: How to Know If It's Abusive and Contest It

Received a rent increase notice? Here's how to assess whether it's justified, and how to contest it if it isn't.

The deadline: 30 days, no exceptions

A rent increase is contested before the Conciliation Commission for leases and rents, within 30 days of receiving it (as a precaution, count from the date of dispatch on the notice). Past this deadline, the increase stands, even if unjustified. The landlord must also give at least 3 months and 10 days' notice before the increase takes effect, and use an official form — an increase notified without this form, or poorly justified, remains contestable even after the 30 days.

The most common grounds for increases

• Reference mortgage rate: an increase in this rate can justify a raise, but only if the resulting rent isn't itself abusive.
• "Neighborhood rents": a frequently invoked ground, but one the landlord has great difficulty proving in court — chances of a successful challenge are generally good here.
• Renovation work or insufficient return on invested equity.
• Indexation clause: only for leases of at least 5 years, tied to the Swiss consumer price index.
• Unmotivated increase: contestable at any time, with no deadline.

The return calculation: your best argument

For buildings purchased or built within the last 30 years, a return calculation is possible: it determines, based on the actual acquisition price of the building, the maximum rent the owner can legally charge to cover costs and earn a reasonable return on invested equity (margin currently capped at 3.25% by the Federal Supreme Court). In most cases where this calculation applies, it reveals that the rent — even before the increase — was already abusive.

During the proceedings, your rent doesn't change

While the challenge is ongoing, you continue paying your current rent, not the increased one. If the proceedings succeed in your favor, the decision applies retroactively to the planned increase date — set aside the difference in case the increase is ultimately confirmed.

No risk in contesting

• The rent can never be set higher by a judge than the amount of the notified increase.
• The procedure is free before cantonal authorities, and you never pay the landlord's legal fees even if you lose.
• There is no blacklist of tenants who contest — this is an urban legend.
• A retaliatory termination following a challenge is rare and generally successfully contested, thanks to the 3-year legal protection after any proceedings.