Initial rent: see the previous rent, and challenge it within 30 days

When you sign a new lease in most Swiss cities with a housing shortage, the landlord must hand you an official form showing what the previous tenant paid. It is the one moment you can see whether the flat got more expensive just because the tenant changed — and you then have 30 days after moving in to challenge the rent.

Where the form is required

Federal law lets cantons with a housing shortage make the form compulsory for new leases (Art. 270 para. 2 CO). The Federal Office for Housing lists the current rules:

Canton	Official form for the initial rent	Vacancy rate (1 June 2026)
Basel-Stadt	Required	0.78%
Bern	Required	1.04%
Fribourg	Required	1.26%
Geneva	Required	0.31%
Lucerne	Required	0.70%
Neuchâtel	Required in part of the canton Flats with 2–5 rooms in Neuchâtel, Laténa (4–5 rooms), Cornaux, Cressier, Le Landeron, Boudry, Cortaillod, Milvignes, Rochefort, La Grande Béroche (3–5 rooms) and Val-de-Ruz; not in La Chaux-de-Fonds, Le Locle, Val-de-Travers and the other communes listed by the BWO.	1.64%
Vaud	Required in part of the canton All districts (including Lausanne) except Aigle.	0.87%
Valais	Not required	1.04%
Zug	Required	0.20%
Zurich	Required	0.52%

Eight of the nine cities this site covers are in cantons or districts where the form is required; the exception is St. Gallen.

What the form must show

The form for a new lease must state (VMWG Art. 19):

• the previous rent and ancillary costs, and your new rent and ancillary costs;
• the reasons for any increase, with an amount for each if there are several;
• the reference interest rate and the consumer price index level the previous rent was based on;
• how to challenge the rent, and the conciliation authorities.

Is your new rent justified?

Bring the previous rent up to date the way an ongoing lease would be: with the change in the reference rate (today 1.25%) and 40% of inflation. The gap between that figure and your new rent is the part of the increase these two reasons do not explain.

Compare your new rent with the previous one

Take the figures from the official form you received with the lease.

Previous net rent (CHF/month) Reference rate of the previous rent 1.25%1.5%1.75%2%2.25%2.5%2.75%3%3.25%3.5% Inflation since the previous rent was set (%) From the index level stated on the form — or leave 0. Your new net rent (CHF/month)

Previous rent adjusted to today’s 1.25% rate and 40% of inflation

CHF 1’748

Your new rent compared with that

+CHF 352 (+20.1%)

A gap does not make the rent abusive on its own. Landlords can justify more with cost increases, value-adding renovations or rents for comparable flats in the area (Art. 269a CO). But the form has to name those reasons — and an increase the form does not explain is the one to question.

When you can challenge the initial rent

You can challenge the initial rent as abusive under Art. 269 and 269a CO (Art. 270 CO) if:

• you felt compelled to sign because of a personal or family emergency, or because of the situation on the local housing market; or
• the landlord raised the rent significantly compared with the previous rent for the same flat.

The law names the local housing market as a ground of its own (Art. 270 para. 1 CO), and the form is compulsory precisely in cantons with a housing shortage (para. 2).

How to challenge it

1. Read the form when you sign, and keep it with your lease.
2. Compare the numbers with the calculator above.
3. Within 30 days after you take over the flat, write to the cantonal conciliation authority (Art. 270 CO). The rent increase guide lists the authorities for every city this site covers.
4. Expect no court costs at the conciliation stage of a tenancy dispute (Art. 113 ZPO).

Challenging the rent does not end your lease, and a termination given because you asserted a tenancy claim in good faith can itself be challenged (Art. 271a CO). If the landlord did not use the form in a canton that requires it, contact the conciliation authority or a tenants’ association quickly — before the 30 days pass.