Challenging your initial rent
You can challenge the rent of a new flat as abusive with the conciliation authority within 30 days of taking it over – if you felt forced into the contract by hardship or the housing market, or if the rent was raised substantially compared with the previous tenant (Art. 270 CO). In cantons where the official form is mandatory, an initial rent without a correct form is not validly agreed, and the 30-day deadline does not apply.
When you can challenge the initial rent
Under Art. 270 para. 1 CO you can challenge the initial rent as abusive with the conciliation authority and ask for it to be reduced if one of two conditions is met:
- you felt forced to sign the lease because of personal or family hardship or because of the situation on the local housing market (lit. a), or
- the landlord raised the rent substantially compared with the previous rent for the same flat (lit. b).
In addition, the rent itself must be abusive under Art. 269 and 269a CO – meaning it yields an excessive return for the landlord or exceeds comparable rents in the area. Where housing is scarce, the market condition is often met. The law does not define "substantial"; the Swiss Tenants' Association uses an increase of around 10 % without renovation as orientation.
The 30-day timeline
- SigningLease and official form
In cantons with a mandatory form, the landlord must give you the form when the lease is concluded.
- Day 0You take over the flat
The 30-day period starts with the handover, usually when you receive the keys.
- Days 1–30Check the previous rent
Compare with the form, or ask the landlord for the previous rent (Art. 256a para. 2 CO).
- Day 30Last day to file
Your written application must be with the conciliation authority where the flat is located.
- Weeks laterConciliation hearing
The authority tries to reach an agreement; many cases end with a settlement.
- ResultLower rent
If successful, the initial rent is reduced and overpaid rent is offset or refunded.
The official form and where it is mandatory
Where housing is scarce, cantons can make the official form mandatory for new leases (Art. 270 para. 2 CO). The form tells you what the previous tenant paid and why the rent was raised. Since 1 October 2025 it must also state the reference rate and the consumer price index level on which the previous rent was based (Art. 19 para. 3 VMWG). That makes hidden increases visible – for example when the previous rent is simply carried over although today's reference rate of 1.25 % is lower than the one it was based on.
According to the Federal Housing Office's list (September 2026 edition), the form is currently mandatory in:
| Canton | Mandatory form | Vacancy rate 1 June 2026 |
|---|---|---|
| Basel-Stadt | yes | 0.78 % |
| Bern | yes (since 1 December 2025) | 1.04 % |
| Fribourg | yes | 1.26 % |
| Geneva | yes | 0.31 % |
| Lucerne | yes | 0.70 % |
| Neuchâtel | partly (listed municipalities, 2–5 rooms) | 1.64 % |
| Vaud | partly (all districts except Aigle) | 0.87 % |
| Zug | yes | 0.20 % |
| Zurich | yes | 0.52 % |
The obligation depends on the vacancy rate and can change every year. Valais has a legal basis but no obligation at present. In all other cantons there is no mandatory form – you can still challenge the initial rent within 30 days.
If the form is missing or incomplete
In a canton with a mandatory form, a lease concluded without the form – or with a form lacking the required information or justification – has a serious consequence for the landlord. The Federal Supreme Court held that the lease remains valid, but the agreement on the amount of rent is void (BGE 120 II 341, confirmed in 4A_168/2014). The tenant can then:
- ask the court to set the initial rent – the 30-day deadline does not apply here, and
- reclaim overpaid rent under the rules on unjust enrichment, even if the lease has been running for some time.
The court does not automatically fall back to the previous tenant's rent; it sets an appropriate rent based on the circumstances. The limit is abuse of rights: a tenant who noticed the missing form and deliberately stayed silent to exploit it later may be refused. Simply paying the rent for a long time is not in itself abusive.
Finding out the previous rent
In every canton, you can ask the landlord to tell you the previous tenant's rent (Art. 256a para. 2 CO). Ask in writing and early – you only have 30 days from the handover. Other clues: old flat advertisements, the previous tenant, or neighbours with similar flats.
Checklist for the first 30 days
- Note the handover date (key handover protocol) – that is when the 30 days start.
- Check whether your canton requires the official form and whether you received it with the lease.
- On the form: previous rent, reference rate and CPI level of the previous rent, and a justification for any increase.
- Compare the new rent with the previous one. If the previous rent was based on a higher reference rate than today's, an unchanged rent can already mean a hidden increase.
- Collect comparable listings for similar flats in the neighbourhood.
- File the application in time – a short written application with a copy of the lease and the form is enough to meet the deadline.
How the procedure works
You file a written application with the conciliation authority where the flat is located. Conciliation in residential tenancy matters is free of court costs (Art. 113 para. 2 lit. c Code of Civil Procedure). The landlord must then justify the rent – with a return calculation or with comparable rents in the area. In practice, many cases are settled at the hearing. A termination in response to your challenge can be contested (Art. 271a CO); see what to do if the landlord refuses.
Moved in a while ago? Then the 30 days have probably passed, but a later cut in the reference rate can still lower your rent. Check it in the calculator.
Frequently asked questions
By when must I challenge the initial rent?
Within 30 days of taking over the flat (Art. 270 para. 1 CO). What counts is the handover, usually when you receive the keys – not the date you signed the lease. The application goes directly to the conciliation authority where the flat is located.
What if I did not receive the official form?
In a canton where the form is mandatory, the agreement on the amount of rent is then void, but the lease itself stays valid (BGE 120 II 341, confirmed in 4A_168/2014). You can ask the court to set the initial rent and reclaim what you overpaid – even after the 30 days. Deliberately staying silent about the missing form in order to exploit it later would be an abuse of rights.
How do I find out what the previous tenant paid?
You can ask the landlord to tell you the amount of the previous rent (Art. 256a para. 2 CO) – in every canton. In cantons with a mandatory form, the previous rent is on the form, and since 1 October 2025 together with the reference rate and inflation level it was based on (Art. 19 para. 3 VMWG).
When is an increase "substantial"?
The law gives no figure. The Swiss Tenants' Association uses an increase of around 10 % over the previous rent without renovation as orientation. In addition, the new rent must be abusive – yielding an excessive return or exceeding comparable local rents.
Do I risk termination if I challenge the rent?
A termination because you assert claims under the lease in good faith can be challenged (Art. 271a para. 1 lit. a CO). During the proceedings and for three years afterwards there is additional protection if the landlord largely loses or settles with you (Art. 271a para. 1 lit. d and e CO).
Which cantons require the official form?
According to the Federal Housing Office's list (September 2026): Basel-Stadt, Bern, Fribourg, Geneva, Lucerne, Zug and Zurich, plus parts of the cantons of Neuchâtel and Vaud. The obligation depends on the vacancy rate and can change every year.
Sources
- Swiss Code of Obligations, Art. 256a, 269–270 and 271a CO (SR 220)
- Federal Housing Office: list of cantons with a mandatory initial-rent form, 2026 (PDF, German)
- Swiss Tenants' Association: initial rent
- Federal Supreme Court 4A_168/2014 (initial rent void without the form, referring to BGE 120 II 341)
- legalis: VMWG amendment of 1 October 2025 (Art. 19 para. 3 VMWG)
Related guides
This guide explains the general legal position under Swiss tenancy law. It is not legal advice for your individual case. For disputes, contact your cantonal conciliation authority or a tenants' association.