Reference interest rate: when your Swiss rent must go down

Most Swiss rents are tied to one number: the mortgage reference interest rate published by the Federal Office for Housing. When it falls, tenants whose rent is based on a higher rate are entitled to a lower rent — but nothing happens automatically. You have to notice, calculate and ask. The rate is 1.25% and has been since 2 September 2025; the next publication is on 1 December 2026.

[Ihr Name]
[Ihre Adresse]

Einschreiben
[Vermieter / Verwaltung]
[Adresse der Vermieterschaft]

[Ort], 11.10.2026

Herabsetzungsbegehren gemäss Art. 270a OR – Mietobjekt [Adresse des Mietobjekts]

Sehr geehrte Damen und Herren

Mein Nettomietzins von CHF 2’000 pro Monat beruht auf einem hypothekarischen Referenzzinssatz von 1,5 %. Der vom Bundesamt für Wohnungswesen publizierte Referenzzinssatz beträgt seit dem 02.09.2025 1,25 %.

Gestützt auf Art. 270a OR und Art. 13 VMWG verlange ich die Herabsetzung des Nettomietzinses um 2,91 % auf CHF 1’942 pro Monat auf den nächstmöglichen Kündigungstermin, d. h. per [nächster Kündigungstermin].

Ich bitte Sie, innert 30 Tagen schriftlich Stellung zu nehmen. Sollten Sie Kostensteigerungen geltend machen, bitte ich Sie, diese im Einzelnen zu beziffern und zu belegen.

Freundliche Grüsse

[Ihr Name]

What the reference rate is

The reference rate is set out in the Ordinance on Leases (VMWG, Art. 12a). Every quarter the banks report their average interest rate on Swiss mortgages; the Federal Office for Housing rounds it to the nearest quarter point and publishes the result as the reference rate. On the latest reporting date, 30 June 2026, the average stood at 1.31% — which rounds to 1.25%.

It is not the Swiss National Bank’s policy rate. A cut by the SNB reaches the reference rate only slowly, through the average of all existing mortgages, many of which run on fixed rates for years.

How the rate has moved

The rate started at 3.5% in 2008, fell in steps to 1.25% in 2020, climbed back to 1.75% at the end of 2023 and has been falling again since 2025. That last stretch matters: anyone whose rent was set or raised between December 2023 and August 2025 is likely paying a rent based on 1.75% or 1.5%.

Do you have a claim?

Find the reference rate your current rent is based on. It is normally stated in the lease or in the last official notice of a rent change. If neither mentions it, ask the landlord — they must be able to say which rate the current rent reflects.

• Your rent is based on 1.5% or more: you have a claim in principle — the federal government says so in every press release on the rate.
• Your rent is based on 1.25%: no claim from the rate; it has not fallen since.
• Your rent is indexed or graduated (fixed steps written into the lease): the reference-rate rules do not apply. Subsidised flats often follow their own rules too.

How much you can claim

The Ordinance sets the rule for increases: each 0.25-point rise in the rate allows the rent to go up by at most 3% while the rate is below 5% (VMWG Art. 13). A fall undoes those steps. One step down is therefore 1 ÷ 1.03, a 2.91% reduction — the figure the federal government quotes. Several steps multiply rather than add up:

• 1.5% → 1.25%: one step, 2.91%. On a CHF 2,000 net rent that is CHF 58 a month.
• 1.75% → 1.25%: two steps, 5.74% (not 5.82%). On CHF 2,000 that is CHF 115 a month.

The claim is on the net rent — utilities and other ancillary costs are not part of it.

What the landlord can offset

The landlord does not have to pass on the full figure. Two things may be set against your claim, counted from your last rent change:

1. Inflation, at 40% (VMWG Art. 16). If consumer prices rose 2% since then, the landlord may offset 0.8%. You can look up the change in the Federal Statistical Office’s inflation calculator — the calculator above takes it as an optional input.
2. Documented increases in maintenance and operating costs. There is no fixed rate in the law. Ask the landlord to itemise any such increase; a refusal without figures is not enough.

How to ask, step by step

1. Check the numbers with the calculator above and note your next termination date — the reduction applies from that date (Art. 270a CO). The dates are in your lease.
2. Send a written request to the landlord or the agency, ideally by registered mail. The calculator drafts one in German, French or English.
3. Wait up to 30 days. The landlord must reply within 30 days of receiving your letter.
4. If they refuse, agree only in part or stay silent, you can turn to your cantonal conciliation authority within the following 30 days. No court costs are charged there in tenancy disputes (Art. 113 ZPO).

The law also protects you for asking: a termination given because you asserted a tenancy claim in good faith can be challenged (Art. 271a CO), and the same protection runs for three years after a conciliation procedure that the landlord largely lost or settled.

The rate can rise again, too. When it does, a landlord may raise the rent — but only on the official cantonal form and with reasons, and you can challenge the increase within 30 days.