Reference rate 1.25%: can you ask for a lower rent?

If your rent is based on a mortgage reference rate of 1.5% or more, you can ask your landlord to lower your net rent, because the rate is now 1.25% (BWO announcement of 1 September 2026; next announcement Tuesday 1 December 2026). For a rent based on 1.5%, the Federal Office for Housing (BWO) gives a reduction claim of 2.91% in principle, but the landlord may set part of it off against inflation and higher costs, so in our hypothetical CHF 2,000 Zurich example, run through the Zurich courts' official calculator, CHF 46.90 a month is left. The request has to be in writing and in time for your lease's next termination date, with the notice period respected.

This page is general information, not legal advice, and it does not say what you should do in your own case. It recommends no landlord, agency or association. The rules are federal (the rent ordinance VMWG as in force on 1 October 2025 and the Code of Obligations as in force on 1 October 2026); the offset figures follow the published practice of the Zurich courts, and other cantons may differ. If you and your landlord disagree, the next step is the cantonal Schlichtungsbehörde (conciliation authority), which tries to settle the dispute and can propose a decision. Below: the rate since 2023, where to find your rate in your lease, how much the claim is, what a landlord may set against it, a worked example and a dated timeline.

What is the reference rate, and what is it now?

The Referenzzinssatz (mortgage reference rate) is the interest rate that Swiss rents are tied to. By law it is based on the quarterly, volume-weighted average interest rate on domestic mortgages, rounded to the nearest quarter point (VMWG Art. 12a), and the BWO publishes it every quarter. It is not the Swiss National Bank's key rate: the BWO says what counts for rents "ist nicht der Leitzinssatz, sondern der hypothekarische Referenzzinssatz" (is not the key rate but the mortgage reference rate).

Today it is 1.25%. In its release of 1 September 2026 the BWO wrote that the rate "beträgt ab dem 2. September 2026 weiterhin 1,25 Prozent" (remains 1.25% from 2 September 2026). The average mortgage rate behind it was 1.31% on 30 June 2026, and the reference rate stays at 1.25% until that average falls below 1.13% or rises above 1.37%. The next figure is due on 1 December 2026, then on 1 March, 1 June, 1 September and 1 December 2027. We make no forecast; we will update this page after 1 December 2026.

The reference rate since 2023, from the BWO releases we opened

Releases of other quarters are not listed because we did not open them. The rate was 1.75% in June 2024, and the March 2025 cut to 1.50% was 0.25 points below the previous rate.

So a lease signed or last adjusted between June 2023 and early September 2025 is likely to be based on 1.50% or 1.75%. Your own lease decides, not this table.

Is your rent based on a higher rate? Where to look

Start with the lease. The BWO says the rate that applies to you "wird oft im Mietvertrag explizit ausgewiesen" (is often stated explicitly in the lease). If the rent has been changed since, look at the last rent-change notice: the landlord has to use the official form and give clear reasons for the change (VMWG Art. 19 Abs. 1).

Which rate counts? The one "der im Zeitpunkt des Vertragsabschlusses massgebend war" (that applied when the lease was signed). If the rent was adjusted later and that change was not challenged, the rate at that adjustment is the starting point. The VMWG adds that it matters whether and how far earlier rate changes led to rent changes (Art. 13 Abs. 4).

Three things the reference rate does not change:

• Your Nebenkosten (service charges). Only the net rent can change; "Die separat vereinbarten Heiz- und Nebenkosten sind davon nicht betroffen" (separately agreed heating and service charges are not affected). Our Nebenkosten guide covers that part of the bill.
• Some kinds of lease. "Davon ausgenommen sind Indexmieten, Staffelmieten sowie geförderte und luxuriöse Wohnungen" (exempt are index-linked rents, staggered rents, and subsidised and luxury flats).
• The starting rent. Challenging the initial rent is a separate procedure with its own deadline, 30 days after moving in (OR Art. 270 Abs. 1). It is not covered here.

How much lower could your rent be?

For a rate rise of a quarter point, the VMWG allows a rent increase of at most "3 Prozent bei Hypothekarzinssätzen von weniger als 5 Prozent" (3% when mortgage rates are below 5%), and when rates fall, rents "sind ... entsprechend herabzusetzen" (are to be reduced accordingly; Art. 13 Abs. 1). A cut is smaller than 3% because it reverses a 3% increase: our arithmetic, 3 ÷ 103 = 2.91%. That is the figure the BWO gives: a rent based on 1.5% carries a reduction claim of 2.91% in principle (BWO, 1 September 2025), and a rent already based on 1.25% has no claim.

Your lease says ... : claim in principle at today's 1.25%, before any offsets (2026)

The 1.75% and 2.00% rows are our arithmetic on VMWG Art. 13 Abs. 1: reversing n increases of 3% each, 3n ÷ (100 + 3n). They are not official BWO figures. The BWO says that for changes larger than a quarter point "gelten andere Überwälzungssätze" (other pass-through rates apply). CHF amounts use the exact fraction (for example 2,000 × 3 ÷ 103 = 58.25), rounded to 5 centimes as the Zurich courts' calculator shows its figures.

These are maximum claims before the landlord's side of the calculation, which comes next.

What can the landlord set against it?

The landlord does not have to accept the full percentage. The same VMWG article lets them set the savings off against cost increases that have occurred in the meantime (Art. 13 Abs. 1). Two offsets are common.

1. Inflation. The rent may rise by "höchstens 40 Prozent der Steigerung des Landesindexes der Konsumentenpreise" (at most 40% of the rise in the consumer price index; VMWG Art. 16), counted from the last time the rent was set. The Zurich courts give the formula: (new index − old index) × 40 ÷ old index, with the index published by the Federal Statistical Office (BFS).
2. General cost increases (maintenance, operating costs). The Zurich conciliation authorities currently work, as a rule, with a lump sum of 0.25% of the net rent per year. In a dispute, the party claiming a change in such costs has to prove it, and the Zurich courts note that this is usually the landlord. The lump sum is Zurich practice, not federal law; other cantons may use a different lump sum or none.

These offsets are what a landlord may claim, not what they must. A landlord can also argue real cost increases instead of the lump sum, since rents are generally not abusive when they are justified by cost increases (OR Art. 269a lit. b). If you cannot agree, the conciliation authority is the next step.

What is left in a worked example?

Hypothetical example, not a real tenancy. Canton Zurich. Net rent CHF 2,000 a month, plus Nebenkosten (not affected). The lease was signed in August 2025, when the reference rate was 1.50% (from 4 March 2025) until it fell to 1.25% from 2 September 2025, and the lease states 1.50%. The rent was set with the index of July 2025 (the month before it was agreed) and has applied unchanged since 1 October 2025. The tenant asks for a reduction from 1 April 2027 (timeline below). The landlord claims both offsets in full. We entered these figures in the Zurich courts' official Mietzinsrechner (rent calculator) on 21 October 2026, with the 0.25% lump sum and September 2026 as the latest index month available then. A request sent later, for example in December 2026, would use a later index month and a slightly longer lump-sum period, so the real figures would differ a little.

Method of the Zurich courts' calculator: each percentage is applied to the old net rent of CHF 2,000, each CHF line is rounded to 5 centimes and the lines are added up: CHF 58.25 − 5.50 − 5.85 = CHF 46.90 a month, CHF 562.80 a year (our arithmetic: 46.90 × 12). The index values 116.0 (July 2025) and 116.8 (September 2026) are the ones the Zurich courts' calculator filled in for those months; they are on an earlier base of the federal consumer price index than the one the BFS publishes now, and only the percentage rise between the two months counts. The inflation offset counts from the last rent setting and the lump sum runs month by month between the two index months, so your figures change with your own dates.

How do you run your own figures?

The Mietzinsrechner asks for the net rent, the month before the announcement and the start date of the last binding rent setting and of the current adjustment, and a choice of lump sum (0.5%, 0.25% or none); its result shows the reference rates, the index values and the 40% inflation share. The tenants' association (Mieterverband) and the homeowners' association (HEV) also offer calculators; both are private associations, one on the tenants' side and one on the landlords' side.

How and by when do you ask?

The law sets the form and the date:

• In writing. "Der Mieter muss das Herabsetzungsbegehren schriftlich beim Vermieter stellen" (the tenant must make the reduction request to the landlord in writing; OR Art. 270a Abs. 2). The BWO suggests sending it "am besten per Einschreiben" (preferably by registered post). That is advice, not a legal requirement.
• For the next termination date. The reduction can be asked for "auf den nächstmöglichen Kündigungstermin" (for the next possible termination date; OR Art. 270a Abs. 1), and the Federal Supreme Court held that for a reduction request "die Kündigungsfrist eingehalten werden muss" (the notice period must be respected; BGE 122 III 20, 1996).
• The notice period itself. For flats, the law sets three months' notice to a customary local date, or to the end of a three-month period where there is no local custom (OR Art. 266c). Many leases name their own dates and periods; yours is in the lease.

You do not need to write the letter from scratch. The Zurich courts say their challenge form "enthält ein vorformuliertes Senkungsbegehren" (contains a pre-written reduction request). We do not publish our own template.

What does the timeline look like for the example lease?

Hypothetical example, not a real tenancy. Same lease as above. Assumption: the lease names 31 March and 30 September as termination dates, with three months' notice. Read your own lease; local dates differ.

1. Tuesday 1 December 2026. The BWO announces the next rate (BWO, 1 September 2026). If it falls, the claim grows. If it stays at 1.25%, a rent based on 1.5% still has its claim; after the last unchanged rate the BWO wrote that such a claim "besteht grundsätzlich weiterhin" (still exists in principle; 1 December 2025).
2. By Thursday 31 December 2026. In this example the three-month notice period to 31 March 2027 starts on 1 January 2027, so the written request has to be with the landlord before then (OR Art. 270a Abs. 1; BGE 122 III 20). If you are close to the date, ask your conciliation authority which day counts.
3. Within 30 days of the request. The landlord "muss innert 30 Tagen Stellung nehmen" (must reply within 30 days; OR Art. 270a Abs. 2).
4. Within a further 30 days, if needed. If the landlord refuses, agrees only in part or does not reply in time, the tenant can apply to the conciliation authority within 30 days. The BWO puts it as at the latest 60 days after the original request.
5. Thursday 1 April 2027. The lower net rent applies from this date if agreed or decided. If the request arrived too late, the next termination date in this lease is 30 September 2027.
6. During 2027. The BWO publishes on 1 March, 1 June, 1 September and 1 December 2027. Each new rate can change the claim for the next termination date.

What if the landlord says no?

A refusal, a partial yes or silence all open the same door: the cantonal Schlichtungsbehörde (conciliation authority), within 30 days. The Zurich courts describe it as a claim for a reduction filed with the conciliation authority when the landlord refuses or does not answer within 30 days. The conciliation authority is also where you can ask questions about dates and offsets in your canton; our rental deposit guide has more on how it fits into a tenancy.

The landlord's reply often cites the offsets above. Whether real cost increases justify more than the lump sum is a question of proof, and in Zurich it is usually the landlord who has to prove them.

The rule runs both ways. If the reference rate rises, a landlord can raise the rent to the next termination date, but must notify it at least ten days before the notice period starts and on a form approved by the canton, with reasons (OR Art. 269d Abs. 1).

What this means for your budget

Rent is a fixed monthly line, so a lower net rent changes every month of the budget. Our guide to a CHF 100,000 salary shows how rent sits next to the other lines.

1. The old rent stays due until the new one is agreed or decided. Nothing changes automatically; the current rent is paid until then.
2. From the effective date, the rent line is the new net rent. In the hypothetical example that is CHF 1,953.10 from 1 April 2027, CHF 46.90 a month less: CHF 422.10 for April to December 2027 and CHF 562.80 in a full year (our arithmetic).
3. Nebenkosten stay as they are. They are a separate line and not affected (BWO).
4. Two dates to track. The BWO announcement on 1 December 2026, and the last day for a request under the lease in question.

Any spreadsheet with a rent line works. Our Swiss Budget Planner, which we sell, has a housing section where you can split net rent and Nebenkosten and update the rent from the month it changes.

Sources and last checked

Checked against these official pages on 21 October 2026 (German pages with an English gloss).

• BWO (Federal Office for Housing), Hypothekarischer Referenzzinssatz (mortgage reference rate): current rate, which rate applies, net rent only, exemptions, procedure, 2.91%, 2027 publication dates.
• BWO, press releases on the reference rate of 1 September 2026, 1 June 2026, 1 December 2025, 1 September 2025, 2 June 2025, 3 March 2025, 3 June 2024, 1 December 2023, 1 September 2023 and 1 June 2023.
• Swiss Confederation, Verordnung über die Miete und Pacht von Wohn- und Geschäftsräumen (VMWG), SR 221.213.11 (rent ordinance), status 1 October 2025: Art. 12a, 13, 16, 19.
• Swiss Confederation, Obligationenrecht (OR), SR 220 (Code of Obligations), status 1 October 2026: Art. 266c, 269a, 269d, 270, 270a.
• Federal Supreme Court, BGE 122 III 20 of 27 February 1996 (university mirror): notice period for reduction requests.
• Zurich courts, Mietzinssenkung (rent reduction), Kostensteigerungen (cost increases), Teuerung (inflation) and Mietzinsrechner (rent calculator).