How much can be the maximum security deposit required by the landlord?

According to the Code of Obligations (art. 257c CO), the deposit may not exceed three months' rent. If the landlord asks for more, you can legitimately decline. The deposit goes to a restricted account in your name, protected by law, and must be returned to you within two weeks of the end of the lease (subject to documented deductions for serious damage).

Can I dispute the initial fee if it seems too high?

Yes. If the proposed fee exceeds the market average of the area (verifiable at cantonal offices), you have 30 days from the signing of the contract to appeal to the conciliation authority. The procedure is free of charge and does not require a lawyer. The conciliation will assess whether the fee is reasonable and may order a reduction.

Is an oral cancellation valid under Swiss law?

No. The Code of Obligations requires that the cancellation be in writing, on an official cantonal form, and delivered in the manner provided. If the landlord cancels only orally, the cancellation is null and void. Always ask for a signed paper cancellation; if the landlord refuses, ignore the verbal cancellation.

How much time do I have to challenge a cancellation that I consider illegitimate?

You have exactly 30 days from receipt of the cancellation to appeal to the cantonal conciliation authority. If you exceed this period, the cancellation becomes valid and the contract is terminated on the dates indicated in the form. Move within the deadline to be entitled to dispute.

If the landlord doesn't return my deposit, what do I do?

The landlord has two weeks from the end of the lease to return the deposit (subject to documented deductions). If you do not do so within this period, please contact the conciliation authority within 30 days, attaching a receipt for payment of the deposit, a contract and a photo of the final state of the property. The conciliation may order the forced return with legal interest.

Aargau rentals: fees and lease rights (cross-border guide)

Di Redazione Frontaliere Ticino · Published on 6 September 2026

Swiss residential building with To Let sign, modern architecture, natural afternoon lighting.

Maximum deposit of 3 months' rent and dispute in 30 days: guide to federal lease law, valid in Aargau and throughout Switzerland.

Context

In brief

Maximum deposit of 3 months' rent, legally tied to the tenant
Notice on cantonal form, contestation within 30 days
Conciliation authority resolves disputes without a lawyer

Key facts

What: Federal tenancy law uniform across Switzerland
Legal reference: Code of Obligations (CO) art. 253 et seq.
Where: Canton of Aargau and all Swiss cantons
Maximum deposit: Three months' rent
Contestation deadline: 30 days with conciliation authority
Notice document: Mandatory official cantonal form

Swiss tenancy law is fully governed by the Code of Obligations (CO), articles 253 and following. A key feature is uniformity: the basic rules on security deposits, notice, and dispute procedures are identical in every canton, including Aargau. This does not mean there are no local differences — each canton can set slightly different notice periods or offer customized notice forms — but the federal legal framework remains homogeneous.

The tenant and landlord must follow precise procedures to avoid disputes before the cantonal conciliation authorities. Violations of these rules can result in contract nullification, forced money returns, and even legal sanctions in cases of systematic fraud.

In the canton of Aargau, as in the rest of Switzerland, the security deposit is one of the central and most delicate aspects of tenancy. The law sets an inviolable maximum limit: the deposit cannot exceed three months' rent. If the landlord requests a higher amount, the agreement is null and void, and the tenant can refuse to pay the excess. This money must be deposited in an account tied to the tenant (not the landlord), thus ensuring legal protection and its return at the end of the contract.

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Operational details

Irregular Termination: How to Recognize and Contest It

A termination is considered irregular if it contains one or more of the following defects: it uses a non-official cantonal form (for example, a generic form copied from the internet); it lacks the correct notice periods according to Aargau law; it is not signed by the landlord or their legal representative; it does not clearly state the property (exact address, apartment number, cadastral data); or it is not delivered in the ways provided by the cantonal procedure (paper, certified mail, etc.).

If you receive a termination that you believe is irregular, you have 30 days to file an appeal with the conciliation authority. There is no need to wait for the termination date to take action: the appeal can be filed as early as the day after receipt, if deemed illegitimate. The conciliation will examine the termination and, if truly irregular, declare it null and void. This means that the contract continues and you do not have to move out.

Scenario 1: Oral Termination

The most common scenario of violation is when a landlord terminates verbally, during a telephone conversation or in person. Note: The Code of Obligations requires a written termination on the official cantonal form. If the landlord terminates only orally, the termination is null and void, unless the tenant explicitly accepts the oral form (not recommended). If the landlord then claims to have terminated orally, always ask for a written termination in writing.

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Key points

When you receive a termination, a rent dispute, or a disagreement over the security deposit, the procedure to follow depends on your role (tenant or landlord) and the nature of the dispute. Below is a practical step-by-step guide for both, allowing you to act correctly and protect your rights according to the Code of Obligations.

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Frequently Asked Questions

How much can be the maximum security deposit required by the landlord?: According to the Code of Obligations (art. 257c CO), the deposit may not exceed three months' rent. If the landlord asks for more, you can legitimately decline. The deposit goes to a restricted account in your name, protected by law, and must be returned to you within two weeks of the end of the lease (subject to documented deductions for serious damage).
Can I dispute the initial fee if it seems too high?: Yes. If the proposed fee exceeds the market average of the area (verifiable at cantonal offices), you have 30 days from the signing of the contract to appeal to the conciliation authority. The procedure is free of charge and does not require a lawyer. The conciliation will assess whether the fee is reasonable and may order a reduction.
Is an oral cancellation valid under Swiss law?: No. The Code of Obligations requires that the cancellation be in writing, on an official cantonal form, and delivered in the manner provided. If the landlord cancels only orally, the cancellation is null and void. Always ask for a signed paper cancellation; if the landlord refuses, ignore the verbal cancellation.
How much time do I have to challenge a cancellation that I consider illegitimate?: You have exactly 30 days from receipt of the cancellation to appeal to the cantonal conciliation authority. If you exceed this period, the cancellation becomes valid and the contract is terminated on the dates indicated in the form. Move within the deadline to be entitled to dispute.
If the landlord doesn't return my deposit, what do I do?: The landlord has two weeks from the end of the lease to return the deposit (subject to documented deductions). If you do not do so within this period, please contact the conciliation authority within 30 days, attaching a receipt for payment of the deposit, a contract and a photo of the final state of the property. The conciliation may order the forced return with legal interest.