Guarantor and Co-Tenant Declaration

A guaranty is one of the few undertakings in Swiss private law that can be entirely void because of how it was written down rather than what it says. OR Art. 493 sets formal requirements, and a declaration that misses one of them does not partially fail — it fails. That is the reason this form is structured the way it is.

The formalities that decide whether it is valid at all

Under OR Art. 493, a personal guaranty must: be in writing; specify the maximum guaranteed amount; and — if the guarantor is a natural person (not a company) — include a handwritten inscription of the maximum amount. If the guarantor is married, the other spouse's written consent is also required under OR Art. 494 for guaranties exceeding CHF 1,500 and not connected to the guarantor's professional activity.

Guarantor or co-tenant — not the same undertaking

A co-tenant (Mitmieter) is jointly and severally liable for all obligations under the rental agreement as a party to the contract — not as a guarantor. A guarantor is a third party who assumes secondary (or, in the case of Solidarbuergschaft, primary) liability for the tenant's obligations. The two roles have different legal bases and different implications for credit assessment and liability extent.

What the declaration collects

• Guarantor or co-tenant personal identification details
• Relationship to the primary tenant
• Financial information: employment, income, existing obligations
• Declaration of no undisclosed debts or insolvency proceedings
• Details of the rental property and tenancy being guaranteed
• Maximum guaranteed amount and duration
• Specific scope of liability (simple or joint guaranty)
• Supporting documents (identity, income proof)
• Legally binding signature

What a guaranty is under OR Art. 492

A guaranty (Bürgschaft / cautionnement) is a contract by which the guarantor undertakes to pay the creditor (the landlord) if the primary debtor (the tenant) fails to fulfil their obligations. In Swiss rental practice, guaranties are commonly used as an alternative to, or supplement of, cash security deposits, particularly when a prospective tenant's financial situation makes landlords cautious.

Swiss law recognises two main types of personal guaranty relevant to rental contexts. A simple guaranty (einfache Bürgschaft / cautionnement simple) means the guarantor is only liable after the landlord has exhausted remedies against the primary tenant. A joint and several guaranty (Solidarbuergschaft / cautionnement solidaire) means the landlord can claim directly against the guarantor without first pursuing the tenant.

In Switzerland, guaranty (Bürgschaft / cautionnement) is governed by OR Art. 492-512. For a personal guaranty to be valid, it must be in writing, specify the maximum amount and duration, and be signed by the guarantor. This form supports the collection of all required information and declarations.

Capping the amount and the duration

Guarantors have the right to limit their liability to a specific maximum amount and time period. The maximum amount should be stated in the guaranty document. Under OR Art. 509, a personal guaranty given for an indefinite period by a natural person for a fixed-term tenancy terminates automatically at the end of the tenancy. Guarantors should clearly specify whether their liability covers only rent or also ancillary costs, arrears, and damage charges.

Withdrawing, and what a change of tenant does

Once given, a guaranty cannot be freely withdrawn. However, if material circumstances change (e.g. the tenancy is extended or the rent increases significantly without the guarantor's consent), the guarantor may have grounds to contest the extended liability. Guarantors should notify the landlord in writing if they wish to terminate a guaranty at the earliest possible date under the terms agreed.

If the tenancy is transferred to a new tenant (Mieterwechsel) without the guarantor's explicit consent, the guarantor's liability does not automatically extend to the new tenant's obligations. Guarantors should review any tenancy transfer carefully and confirm in writing whether they agree to extend their guaranty to cover the new tenant.

Using the form