What Is Referenzzinssatz and How Does It Affect Your Rent?

If you have ever received a letter from your landlord announcing a rent increase — or read about Swiss tenants winning a rent reduction — there is one term at the centre of it all: the Referenzzinssatz.

This single number, published quarterly by the Swiss government, is the most important lever in Swiss tenancy law. It determines when landlords can raise rents, when tenants can demand reductions, and by how much. Understanding it is not just useful — it can save you hundreds of francs per year.

What Is the Referenzzinssatz?

The Referenzzinssatz (reference interest rate) is the national average interest rate on Swiss mortgage debt, rounded to the nearest 0.25%. It is calculated by the Swiss National Bank and published quarterly by the Federal Office of Housing (Bundesamt für Wohnungswesen / BWO).

As of early 2026, the rate is 1.75% — having fallen from a peak of 1.75% in 2023 after a long period at 1.25%.

The rate is calculated from the volume-weighted average interest rate on all outstanding domestic mortgage debt in Switzerland. It is not the same as the Swiss National Bank policy rate, though they move in the same direction.

Why Does It Matter for Rent?

Swiss rental law (OR Art. 269a and VMWG) directly links rents to the Referenzzinssatz. The principle is simple:

• If the reference rate rises, landlords are permitted to raise rents
• If the reference rate falls, tenants have the right to demand a rent reduction

This mechanism is designed to prevent landlords from charging rents that are disproportionate to their financing costs. It also means that when mortgage conditions improve, tenants should benefit too.

How Much Can Rent Change?

The formula is set by law:

| Change in rate | Permitted rent adjustment | |---|---| | Rate rises by 0.25% | Landlord may increase rent by ~2% | | Rate falls by 0.25% | Tenant may demand rent reduction of ~2.5% |

These percentages are approximate — the exact calculation also depends on how long the apartment has been rented at the current level and whether previous adjustments have already been made.

Additionally, landlords can claim:

• 40% of the general cost-of-living increase (Teuerung) since the last rent adjustment
• Actual cost increases for building maintenance, operating expenses, or capital investments

Example

Say your rent is CHF 2,000/month and the Referenzzinssatz rises from 1.5% to 1.75%:

• The permitted rent increase is approximately 2% = CHF 40/month
• Your new rent could be raised to CHF 2,040

Conversely, if the rate falls from 1.75% to 1.5%, you could claim a reduction of approximately 2.5% = CHF 50/month.

When Can a Landlord Raise Rent?

A landlord may raise rent after a Referenzzinssatz increase only if:

1. The increase is notified using the official cantonal form (Formular für Mietzinserhöhungen)
2. The notice is sent by registered post
3. The notice arrives at least 10 days before the beginning of the new rental period
4. The landlord specifies the legal justification (reference rate increase, cost increase, or inflation)

If any of these conditions are not met, the rent increase is legally invalid. You can challenge it.

Your Right to a Rent Reduction

When the Referenzzinssatz falls, your landlord is not obligated to lower your rent automatically. You must actively request a reduction.

The process:

1. Check the current rate at the BWO website (bwo.admin.ch)
2. Compare it to the rate applicable when your current rent was set — this is stated in the rent adjustment notice or, for original rents, in your contract
3. Write to your landlord (by registered post) requesting a reduction, citing the legal basis (VMWG Art. 13)
4. Give your landlord a deadline of 30 days to respond
5. If refused or ignored, file a complaint with the cantonal Schlichtungsbehörde (conciliation authority) — this is free of charge

Important: Timing Your Request

The reduction takes effect from the next legal termination date (Kündigungstermin) after your request. In Zürich, these are 31 March, 30 June, and 30 September. Send your letter well before the deadline.

Historic Rate Changes

The Referenzzinssatz has moved significantly over the past decade:

| Period | Rate | Direction | |---|---|---| | 2017–2022 | 1.25% | Stable (record low) | | June 2023 | 1.50% | First rise in 15 years | | September 2023 | 1.75% | Further rise | | March 2025 | 1.75% | Holding | | June 2025 | 1.50% | First fall — reduction rights triggered |

The June 2023 increase was the first in 15 years. Hundreds of thousands of Swiss tenants received rent increase notices. The subsequent fall in 2025 meant tenants had the right to claim reductions.

Is the Referenzzinssatz the Only Reason Rent Can Change?

No. Landlords can also justify rent increases on:

• General cost increases — up to 40% of accumulated inflation since the last adjustment
• Renovation and maintenance costs — if they improve the property (not just routine maintenance)
• Market rent — if the current rent is demonstrably below comparable market rents (this is rare and harder to justify)

Tenants can challenge any of these justifications before the Schlichtungsbehörde.

How Does This Affect Cooperative Housing?

Cooperative rents (Genossenschaftswohnungen) are also subject to the Referenzzinssatz. However, because cooperatives set rents based on actual costs (not market rates), adjustments tend to be smaller and less frequent. The long-term rent stability of cooperative housing is one of its key advantages — rent increases are tied to actual cost changes, not speculation.

If you are on a cooperative waitlist or looking for more stable housing, explore what is available on SwissCoHousing, which monitors 150+ cooperative sources in real time.

Frequently Asked Questions

How often is the Referenzzinssatz published?

It is published quarterly — in March, June, September, and December — by the Federal Office of Housing (BWO). You can find the current rate at bwo.admin.ch.

My landlord raised my rent citing the Referenzzinssatz — can I challenge it?

Yes. Check that the increase was notified correctly (on the official cantonal form, by registered post, with 10 days' notice). Also verify that the calculation is correct and that no prior adjustments have already accounted for the rate change. If anything is wrong, file a complaint with the Schlichtungsbehörde within 30 days of receiving the notice.

Does the Referenzzinssatz apply to all rental apartments in Switzerland?

Yes, it applies to all residential rental agreements governed by Swiss tenancy law, including unfurnished and furnished apartments. It does not apply to holiday lets or short-term leases under 3 months.

What is the Schlichtungsbehörde and is it free?

The Schlichtungsbehörde (conciliation authority) is a cantonal mediation body that handles rental disputes. Proceedings are free for both parties. If conciliation fails, the case moves to a court. Most disputes are resolved at the conciliation stage.

How do I find out what rate applied when my current rent was set?

Look at the most recent rent adjustment notice you received from your landlord — it should state the Referenzzinssatz that was applicable at the time. If you never received one, check your original lease or contact your landlord in writing to request this information.