Quick answer: The mortgage reference interest rate currently stands at 1.25% (since September 2, 2025, last confirmed unchanged on June 1, 2026). Whether a rent increase you have received is valid can be clarified with a 5-step check: form, deadline, justification, amount and – if necessary – a timely objection with the conciliation authority.
Current Reference Interest Rate & Development
The mortgage reference interest rate is the key figure for many rent adjustments in Switzerland. It currently stands at 1.25%, valid since September 2, 2025, and was last confirmed unchanged on June 1, 2026. The next publication is scheduled for September 1, 2026.
For context: in 2023, the reference interest rate rose in two steps from 1.25% to 1.75%. Two decreases followed, bringing it back to its starting value of 1.25% as of September 2, 2025. These movements are the main reason why many tenants have received a rent increase – or a valid basis for a rent reduction – in recent years.
Formal Requirements: Nothing Is Valid Without the Official Form
A rent increase is subject to strict formal requirements. If any of these requirements is violated, the increase is void – regardless of whether the underlying reason would itself be justified.
- Official form mandatory: The notice must be issued on the official, cantonally approved form. Without this form, the increase is void.
- Timely delivery: The notice must arrive at least 10 days before the start of the ordinary notice period. It only takes effect on the next termination date.
- Duty to state reasons: The reason for the increase must be stated on the form concretely and comprehensibly. General phrases without substance are not sufficient.
- No coupled threat of termination: A simultaneous threat of termination in case the increase is not accepted is not permitted.
What Reasons Justify a Rent Increase?
The reference interest rate is just one of several permissible grounds for an increase. The following reasons are also commonly cited:
- Cost-of-living adjustment: a maximum of 40% of the Swiss consumer price index
- Actual increase in maintenance and operating costs
- Value-adding investments (improvements that create added value – pure replacement investments do not count)
- Comprehensive renovations, which can be charged to the rent on a pro-rata basis
- Local or neighborhood rent comparisons, which are occasionally used as justification
Important: the stated reason must be specifically named on the form, and the requested increase must match that reason. A blanket reference to "increased costs" without further details is not sufficient.
The 5-Step Check for Your Rent Increase
The following five steps let you systematically check whether a rent increase you have received is valid:
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1
Check the form
Was the official, cantonally approved form used? Without this form, the rent increase is void – regardless of how justified the reason may be in substance.
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2
Check the deadline
Was the notice delivered at least 10 days before the start of the ordinary notice period and set for the next termination date? If either is missing, the increase is invalid.
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3
Check the justification
Does the form state a concrete, comprehensible reason – such as the reference interest rate, inflation, rising costs, or investment? General phrases without substance do not meet the requirements.
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4
Assess the amount
Does the requested increase match the stated reason – for example around 3% per 0.25-point step in the reference interest rate, or a maximum of 40% of inflation? If in doubt, an online rent calculator can help with a rough assessment.
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5
Respond
In case of a formal defect or an implausible justification: file a written objection with the conciliation authority at the location of the rented property within 30 days.
To put the amount into context (step 4): a widely cited rule of thumb holds that an increase in the reference interest rate of 0.25 percentage points justifies a rent increase of around 3%; conversely, a decrease of 0.25 percentage points gives rise to a claim for a rent reduction of around 2.91%. These figures are not an officially published federal or cantonal table, but a common calculation practice – the actual calculation is contract-specific and depends on the previous base rate of the tenancy in question. For a more precise assessment in individual cases, online rent calculators are usually used.
Objection: Deadline and Jurisdiction
If the check reveals a formal defect or an implausible justification, the rent increase can be contested. The deadline for this is 30 days from receipt of the notice. The objection must be made in writing and submitted to the conciliation authority at the location of the rented property – not at the landlord’s place of residence.
Frequently Asked Questions
What is the current reference interest rate?
The mortgage reference interest rate is currently 1.25%, valid since September 2, 2025. It was last confirmed unchanged on June 1, 2026; the next publication is scheduled for September 1, 2026.
By how much may the rent increase when the reference interest rate rises?
The common calculation practice is: if the reference interest rate rises by 0.25 percentage points, landlords may increase the rent by around 3%. This rule of thumb is not officially published as a fixed table – the actual calculation depends on the tenancy’s previous base rate and is usually determined using a rent calculator.
What deadline applies for a valid rent increase?
The notice must arrive on the official form at least 10 days before the start of the ordinary notice period. The increase only takes effect on the next ordinary termination date.
How much time do I have to contest a rent increase?
The objection period is 30 days from receipt of the notice. The objection must be submitted in writing to the conciliation authority at the location of the rented property – not at the landlord’s place of residence.
Conclusion
A rent increase is only valid if the form, deadline, and justification are correct and the amount matches the stated reason. The 5-step check provides quick guidance for this. If in doubt, a careful review is worthwhile – the 30-day objection period from receipt of the notice is short and should not be missed.
All figures and legal references in this article are disclosed and linked → Sources.
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