Challenging a rent increase: your rights in a long tenancy

If your rent goes up, you have 30 days to challenge it free of charge before the conciliation authority – and an increase without the official form is void from the outset. Conversely, when the reference interest rate falls you have a claim to a reduction, but you must actively request it. Anyone who has lived in the same apartment for decades is in a particular position: the rent is often below market level, the income is fixed, and fear of termination stops many people from using their rights. That fear is usually unfounded.

The reference rate: when are you entitled to a reduction?

The mortgage reference interest rate is published by the Federal Housing Office and is the basis for rent adjustments. It currently stands at 1.25 per cent (reduced in March 2025).

What matters for your calculation is not the rate at the start of the tenancy but the rate underlying your last rent adjustment. If your rent has never been adjusted, the rate at the time the contract was signed applies. You will find it in the tenancy agreement or on the last official form.

Change	Entitlement	On CHF 2 000 net rent
Fall of 0.25 percentage points	2.91 % reduction	around CHF 58 less per month
Fall of 0.50 percentage points	5.66 % reduction	around CHF 113 less per month

The key sentence: the reduction does not arrive automatically. You must request it in writing, effective on the next possible termination date and observing the notice period. This is exactly where long-standing tenants leave the most money on the table – often over many years.

General cost increases and value-adding investments may be offset against it. So the full percentage rarely arrives, but almost always part of it does.

When is an increase valid at all?

Three formal requirements, and breaching any one of them makes the increase void:

1. Notification on the official form approved by the canton – a letter is not enough.
2. Reasons showing what the increase is based on.
3. No threat of termination in connection with the increase.

An increase also takes effect at the earliest on the next termination date and must observe the notice period plus ten days.

A void increase does not have to be paid – even without a challenge. In practice a factual letter pointing out the defect is still advisable, so that the matter is documented.

Renovation and rent: what is permitted

In long tenancies the increase often follows a comprehensive renovation. A surcharge is permitted only for the value-adding portion – pure repairs and maintenance do not justify one. Replacing a broken boiler with an equivalent one is maintenance; installing a lift where there was none is value-adding.

For comprehensive renovations, practice often recognises a flat portion of the costs as value-adding. Ask for a breakdown if the reasons given state only a total.

A special case with a later-life angle: if the renovation includes barrier-free work – a level-access shower, a ramp, a lift – that is a genuine benefit to you, but it also justifies a surcharge. What such a conversion costs, and who else contributes, is on the topic page Adapting your home.

How to challenge – in four steps

1. Note the date. The 30-day period runs from receipt of the official form. It is a forfeiture period: miss it and the right to challenge is gone.
2. Check the reasons. Reference rate, inflation, cost increases, value-adding investments – ask to be shown figures, not assertions.
3. File the conciliation request. In writing, with the conciliation authority at the location of the property. The procedure is free of charge and no lawyer is needed. Many authorities provide forms.
4. Keep paying as before. The previous rent applies until a decision. Any difference is settled afterwards.

Take someone with you. The cantonal tenants’ association advises its members, and Pro Senectute helps with correspondence in many cantons.

The fear of retaliatory termination

It is the most common reason long-standing tenants forgo their rights – and it is largely unfounded in law.

A termination issued because you asserted rights under the tenancy can be challenged as retaliatory. In addition, after conciliation or court proceedings there is a period of protection against termination, provided the landlord did not fully prevail.

That does not mean notice can never be given. It means a termination in temporal proximity to a challenge requires explanation – and that you can contest that too. Accepting an increase that was not permissible, by contrast, means paying it for years.

If you receive supplementary benefits

Here an additional calculation is needed. For supplementary benefits, housing costs are only recognised up to maximum amounts set by canton and region. If your rent rises above that maximum, you bear the difference entirely – an increase of CHF 100 can mean CHF 100 less in real terms.

Two things follow. Report every rent change to your compensation office, including a reduction. And before moving, find out where the maximum lies for your region – before you sign anything.

Summary

• An increase without the official form, without reasons, or with a threat of termination is void and need not be paid.
• The period for challenging is 30 days from receipt and is a forfeiture period. Conciliation is free of charge.
• When the reference rate falls there is a claim to a reduction – but only if you actively request it.
• After a renovation only the value-adding portion justifies a surcharge; ask for a breakdown.
• Fear of retaliatory termination is the most common reason to forgo rights – and is largely unfounded in law.
• If you receive supplementary benefits: report every rent change and know the regional maximums.