Increasing the rent lawfully under art. 269d CO
A rent increase is governed by the relative method of art. 269 ff. CO: the landlord may pass on only what has changed since the last valid fixing of the rent, and only in the prescribed forms. An increase given in the wrong way is void, and the lease continues at the former rent. This guide sets out the admissible grounds, the calculation ground by ground, the 10-day time limit, the termination date, and the errors that void the increase. imoz calculates the admissible increase and prepares a reasoned notice; that notice does not replace the canton's official form, on which the increase must be notified.
Updated 09.2026
The procedure in four steps
- 1Identify the admissible ground or grounds
Determine what has changed since the last valid fixing of the rent. The grounds under the relative method are exhaustive (art. 269a CO): a change in the reference interest rate, inflation (CPI), increases in maintenance and operating costs, additional services and value-enhancing improvements, rents customary in the locality, or a validly notified reservation of a prior increase. The reference rate is always compared between the date of the last fixing and today, according to the value published by the Federal Housing Office: if it has risen since then, it opens a right to an increase; if it has fallen, it gives the tenant a right to a reduction that must be deducted from the other factors. The ground of rents customary in the locality follows a different logic and requires proof by comparables or official statistics (art. 11 OBLF): it cannot be ticked like the CPI and calls for professional validation.
- 2Calculate the increase ground by ground, without double counting
Each factor starts from its own reference date and is calculated on the net rent in force. Reference rate: about 3% per 0.25% band when rates are below 5% (art. 13 OBLF). Inflation: pass-through of at most 40% of the rise in the CPI on the equity portion (art. 16 OBLF). Costs: the actual increase, duly substantiated. Value-enhancing improvements: for major renovations, 50 to 70% of the cost is deemed to add value (art. 14 OBLF). If the reference rate has fallen since the last fixing, deduct that fall (scale in art. 13 OBLF) from the other factors before giving notice: omitting it makes the increase abusive and reducible in conciliation. Never count the same factor twice.
- 3Give notice on the official form, on the correct termination date
The notice must reach the tenant on the official form approved by the canton, stated in its grounds and quantified by factor, at least 10 days before the beginning of the notice period, and take effect on the next termination date (art. 269d para. 1 CO). The time limit runs from receipt, not from dispatch: send by registered mail and keep proof. For a family dwelling, as a precaution address a separate notice to each spouse or registered partner: notice to a single holder exposes the increase to challenge, so it is preferable to notify each of them individually.
- 4Handle a challenge or enter a reservation
The tenant has 30 days from receipt to bring the matter before the conciliation authority (art. 270b CO). Without a challenge within that time limit, the increase stands. A termination given because the tenant challenged the increase is voidable (art. 271a CO). If you pass on only part of the admissible increase, record the balance as a quantified reservation on the form (art. 18 OBLF), failing which it is lost.
1.The admissible grounds and the relative method
art. 269, 269a COThe relative method does not ask whether the rent is objectively profitable, but what has changed since the last valid fixing of the rent. The state of the factors at that reference date is compared with their state today, and only the variation that occurred between the two may be passed on, in either direction: a factor that has fallen since the last fixing, such as the reference rate, is deducted from the factors pointing upward.
The grounds are exhaustive: a change in the reference rate, inflation, increases in maintenance and operating costs, additional services and value-enhancing improvements, adjustment to rents customary in the locality, and a validly notified reserved increase. Each factor has its own reference date and never goes back beyond the last increase in which it was already taken into account. The ground of rents customary in the locality nonetheless requires proof by comparables or official statistics (art. 11 OBLF) and combines poorly with the other relative grounds.
2.The reference rate and the calculation scale
art. 12a, 13, 16 OBLFThe reference mortgage rate, a single rate published quarterly by the Federal Housing Office (art. 12a OBLF), moves in steps of 0.25%. A rise of 0.25% authorizes, on the net rent, an increase of about 3% when rates are below 5%, 2.5% between 5 and 6%, and 2% above (art. 13 OBLF).
This scale combines with the pass-through of inflation (at most 40% of the rise in the CPI, art. 16 OBLF) and with cost increases, starting from the latest reference values and without duplication. Symmetrically, a fall in the rate gives the tenant a right to a reduction on the same scale (art. 13 para. 4 OBLF): where it has occurred since the last fixing, it must be deducted from the upward factors before any notice.
3.The official form, the 10-day time limit and the termination date
art. 269d para. 1 CO, art. 19 OBLFThe notice of increase must use the official form approved by the canton, in its language, and state the former rent, the new rent, the effective date, the quantified grounds and the right to challenge (art. 19 OBLF). A letter, an email or an amendment to the lease is not sufficient: the increase would be void.
The notice must reach the tenant at least 10 days before the beginning of the notice period and take effect on the next termination date (art. 269d para. 1 CO). The time limit is counted from receipt. The increase concerns only the net rent: adjusting the advance payments for ancillary costs is not an increase within the meaning of art. 269d.
4.Challenge, reservation and excluded lease types
art. 269b, 269c, 270b CO, art. 18 OBLFThe tenant may challenge the increase as abusive within 30 days of receipt, before the conciliation authority (art. 270b CO). The form may be correct and the increase nonetheless reduced if the amount exceeds what the relative method allows. Under this method, whatever is not passed on is lost, save for a quantified reservation notified on the form (art. 18 OBLF).
The index-linked lease (art. 269b CO, term of at least five years, indexation to the CPI) and the stepped-rent lease (art. 269c CO) follow their own rules and fall outside the regime of art. 269d.
What makes the increase void
An increase notified by letter, email, amendment to the lease, or on the form of another canton is void (art. 269d para. 2 CO). It must use the official form in force in the canton where the property is located, in its language, stating the right to challenge and the 30-day time limit. A further defect entails the same nullity: coupling the increase with a termination or a threat of termination (art. 269d para. 2 let. c CO). Do not therefore attach to the notice any wording of the type: failing agreement, the lease will be terminated. The lease then continues at the former rent, even where the increase was justified on the merits.
The increase must be stated in its grounds and quantified on the form, precisely enough for the tenant to assess whether it is well founded. Ticking boxes without breaking down the figures, or invoking a vague adjustment to the market, weakens or voids the increase. The statement of grounds cannot be supplemented after the fact, and a lump-sum amount not apportioned among the factors exposes the increase to challenge.
The notice must reach the tenant at least 10 days before the beginning of the notice period, not 10 days before the termination date, and take effect on the next termination date calculated according to the statutory or contractual notice period and the customary dates. An error of time limit or termination date does not void the increase, but postpones it to the following termination date, often a year later. The time limit is counted from receipt, the proof of which lies with the landlord.
Mechanically adding rate, CPI and costs when part of them overlaps, or passing on both a value-enhancing improvement at the current rate and the rise in the rate on the same capital, leads to an abusive increase, reduced in conciliation. Conversely, forgetting to deduct a fall in the reference rate that has occurred since the last fixing inflates the increase and exposes it to the same reduction. A further precaution: for a family dwelling, a single notice addressed to the couple is fragile; a separate notice to each spouse or registered partner is preferable, by analogy with art. 266n CO applicable to termination, even though the law does not expressly render void an increase notified in this way.
Calculate the admissible increase and generate the notice
imoz applies the relative method starting from the reference dates of your lease: reference rate, inflation, cost increases and value-enhancing improvements, without double counting, deducting any fall in the rate that has occurred since the last fixing. The tool calculates the admissible increase, proposes a quantified reservation for any shortfall, checks the notice period and the termination date, then prepares the reasoned notice, duplicated for each holder in the case of a family dwelling. That notice is a basis only: the increase is valid only if notified on the canton's official form, which imoz does not replace.
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Frequently asked questions
What time limit and termination date apply to notifying an increase?+
The notice must reach the tenant at least 10 days before the beginning of the notice period, and the increase takes effect on the next termination date (art. 269d para. 1 CO). The termination date is calculated according to the statutory or contractual notice period and the local customary dates. The time limit is counted from receipt of the notice, not from its dispatch.
Is the official form mandatory?+
Yes. Without an official form approved by the canton, duly stating its grounds, the increase is void (art. 269d para. 2 CO). A letter, an email or an amendment to the lease does not replace the form. It must be the form of the canton where the property is located, in its language, and must state the right to challenge before the conciliation authority within 30 days. The same nullity strikes an increase coupled with a threat of termination or notified during the period to challenge an earlier increase (art. 269d para. 2 CO).
By how much can the rent be increased after a rise in the reference rate?+
A rise of 0.25% in the reference rate authorizes, on the net rent, about 3% when rates are below 5% (art. 13 OBLF), 2.5% between 5 and 6%, and 2% above. This percentage combines, without double counting, with the pass-through of inflation and cost increases, starting from the latest reference values of the previous fixing. Conversely, if the rate has fallen since that fixing, the corresponding fall is deducted from the other factors.
Can the tenant refuse the increase?+
The tenant does not refuse it, but challenges it. Within 30 days of receipt, the tenant may bring the matter before the conciliation authority to have the increase declared abusive (art. 270b CO). If no challenge is made within that time limit, the increase stands. A termination given because the tenant challenged an increase is voidable (art. 271a CO).
Can this method be applied to an index-linked lease?+
No. The index-linked lease (art. 269b CO, term of at least five years) passes on 100% of the variation in the CPI according to its own rules and falls outside the regime of art. 269d. The stepped-rent lease (art. 269c CO) likewise follows its own regime. Notifying a relative-method increase on such a lease is an error of regime.
This guide is general information on Swiss tenancy law (art. 269 ff. CO, OBLF), not individual legal advice. Particular situations, notably the family dwelling, rents customary in the locality, yield and mixed works, warrant validation by a professional. imoz is a tool for calculating and generating the notice of increase, it does not provide legal advice.