Mietzinserhöhung in Switzerland: How Rent Increases Are Calculated

A hypothekarischer Referenzzinssatz change does not automatically raise anyone's rent. It only sets a ceiling on how much a landlord is allowed to pass on, and the actual percentage depends on where that reference rate currently sits, not on a flat number a landlord can apply regardless of the rate's level.

This page works through the mechanism end to end: the reference interest rate itself, the tiered Art. 13 VMWG table that converts a rate change into a maximum rent increase, the Teuerung and Kostensteigerung components that can add further increases on top, and the Art. 269d OR notice procedure a landlord must follow to impose any of it. It is part of our wider Swiss tenant law coverage, itself part of the broader guide to Swiss law.

Information last verified on 21 July 2026. This page provides general legal information about Swiss law and does not constitute legal advice in an individual case.

The hypothekarischer Referenzzinssatz

Most rent increases in Switzerland start with a single published figure: the hypothekarischer Referenzzinssatz, the reference interest rate for residential mortgages. As of this writing it stands at 1,25 percent, a level that has been unchanged since it was first published on 2 September 2025 and confirmed again on 1 June 2026, effective 2 June 2026.

The rate is not set by discretion. Art. 12a VMWG defines it as a quarterly figure, based on the volume weighted average interest rate for domestic mortgage claims, commercially rounded to the nearest quarter percentage point. The Eidgenössisches Departement für Wirtschaft, Bildung und Forschung, abbreviated WBF, publishes the figure every quarter.

The next publication is due 1 September 2026. Because the rate moves on a fixed quarterly schedule and this page can only report the figure as it stood on the verification date above, a reader relying on this for an active rent dispute should check the current published rate at bwo.admin.ch before doing any calculation, rather than assuming the number above is still current.

Art. 13 VMWG: a tiered ceiling, not a flat percentage

This is the section most secondary sources oversimplify. Art. 13 VMWG does not say every 0,25 point move in the reference rate justifies a flat 3 percent rent increase. It sets three different maximums, depending on where the reference rate itself currently sits.

At today's reference rate of 1,25 percent, a landlord who can point to a genuine 0,25 point rise in the reference rate may pass on at most 3 percent of the rent as an increase tied to that single step. If the reference rate ever climbs into the 5 to 6 percent band, the same 0,25 point step would only justify a 2,5 percent increase, and above 6 percent only 2 percent. The band that applies is whichever one the CURRENT rate falls into at the time of the increase, not a number fixed for all time.

A worked example makes this concrete. A tenant paying CHF 1,800 per month faces a landlord passing on one full 0,25 point reference rate increase while the rate itself remains below 5 percent. The maximum increase available under Art. 13 Abs. 1 lit. c VMWG is 3 percent of the existing rent, or CHF 54 per month, bringing the new rent to at most CHF 1,854.

When the rate falls: the reciprocal decrease is not in the ordinance

Art. 13 Abs. 1 VMWG also addresses the opposite direction. It states only that when the reference rate falls, rents are to be reduced "entsprechend," meaning correspondingly, or that the resulting savings may instead be offset against cost increases that have occurred in the meantime. No decrease percentage is written into the text.

The figures often quoted for a decrease, such as roughly 2,91 percent for the current below 5 percent band, are not statutory wording. They come from a standard reverse calculation practitioner bodies such as HEV Schweiz and the Mieterverband publish as guidance, working backward from the 3 percent increase figure so that a full round trip up and then down nets back to the original rent. The same logic applied to the other two bands gives roughly 2,44 percent for the 5 to 6 percent band and roughly 1,96 percent above 6 percent, though these two are not published anywhere as an official figure either.

Treat any decrease percentage you see quoted for Art. 13 VMWG as the standard offsetting calculation practitioners use, not as a number the ordinance itself states. The legal entitlement is to a corresponding reduction, and the practice convention is simply the accepted way of computing what "corresponding" means in practice.

Teuerung: the inflation component

Separate from the reference rate mechanism, Art. 16 VMWG allows a landlord to increase rent to offset general inflation on the portion of capital the landlord bears the risk on. The cap is 40 percent of the increase in the Landesindex der Konsumentenpreise, the national consumer price index, over the relevant comparison period.

This is a genuinely separate ground from the reference rate increase discussed above. A landlord can in principle rely on both in the same notice, provided each is calculated and justified on its own terms rather than blended together without explanation.

Kostensteigerung: the broader cost category

Art. 12 VMWG describes a wider category of cost increases that can justify a rent adjustment under Art. 269a Bst. b OR, and the reference rate mechanism in Art. 13 VMWG is simply the specifically tabled sub case of this broader category. The ordinance names increases in fees, property taxes, ground rent payments, insurance premiums, and maintenance costs as qualifying cost increases.

One exclusion is worth flagging. Costs arising purely from a change of ownership, a Handänderung, are expressly excluded from counting as a cost increase under this article. A new owner cannot use the fact of having recently bought the building as its own justification for a higher rent.

Art. 269d OR: the procedure for imposing an increase

None of the grounds above take effect automatically. A landlord who wants to raise the rent for any of these reasons must follow the procedure set out in Art. 269d OR, and getting this wrong voids the increase regardless of whether the underlying calculation was correct.

The landlord may raise the rent effective on the next possible termination date for the lease, at any time. The increase must be communicated to the tenant, together with the reasons for it, on the cantonally approved form, and this notice must reach the tenant at least ten days before the start of the applicable notice period.

Art. 269d Abs. 2 OR lists three independent triggers that make the increase void, meaning nichtig, outright. The increase is void if the landlord fails to use the prescribed form, fails to give reasons for it, or bundles a threat or an actual termination together with the increase notice. Any one of these three defects is enough on its own; a tenant does not need to show all three to challenge the notice.

Do not confuse this with the landlord's termination form

It is worth being precise about a distinction that is easy to blur. The Art. 269d form discussed here is specifically for imposing a rent increase or another one sided change to the lease. It is a different document from the form a landlord must use under Art. 266l OR to terminate a tenancy outright, which is void under Art. 266o OR if the wrong form is used.

A rent increase notice that uses the wrong form is void under Art. 269d, but the tenancy itself continues unaffected at the prior rent. A termination notice that uses the wrong form is void under Art. 266o, and the tenancy also continues, but for an entirely different reason connected to ending the lease rather than adjusting its price. Neither defect automatically triggers the other, so a tenant checking one should not assume the other has also gone wrong.

What changed on 1 October 2025, and what did not

An amendment in force since 1 October 2025 (AS 2025 191) added a disclosure duty covering the reference interest rate and the consumer price index level behind a tenant's previous rent. It is worth being precise about which form that duty attaches to, because it is easy to assume it applies here.

It does not. VMWG Art. 19 Abs. 3 attaches the new disclosure to the form a canton makes mandatory at the conclusion of a NEW lease under Art. 270 Abs. 2 OR, which is covered on our page about challenging the initial rent. The ordinary mid-tenancy increase notice under Art. 269d is unchanged by it.

The same amendment also inserted VMWG Art. 19a, which is a separate rule entirely: for staggered rents, written notice of each step may be given no earlier than four months before that step takes effect.

Challenging an increase

A tenant who receives a rent increase notice and believes it is not justified, whether because the arithmetic is wrong, the wrong form was used, or no reasons were given, can bring the matter to the Schlichtungsbehörde. The 30 day window and the process itself are covered in depth on our initial rent challenge page, since the same conciliation authority and much of the same procedure apply to both an initial rent dispute and a challenge to a later increase.