Two ways, compared
| Co-tenant with joint liability | Surety (Bürgschaft) | |
|---|---|---|
| Signs the lease | Yes | No, a separate declaration |
| Liable for | The whole debt, as long as it is not paid (Art. 143 and 144 OR) | At most the amount named in the deed (Art. 499 OR) |
| Form | The lease itself | Written, with a maximum amount in figures (Art. 493 para. 1 OR) |
| Notary | No | Yes for private persons above CHF 2,000. Up to CHF 2,000 the amount written by hand is enough (Art. 493 para. 2 OR) |
| Married helper | No special rule in these articles | The spouse must consent in writing (Art. 494 OR) |
How a surety works
- Simple surety. The landlord can turn to the surety only after the tenant has, for example, gone bankrupt or been pursued to a definitive loss certificate (Art. 495 OR).
- Joint surety. If the word "solidarisch" is added, the landlord can claim from the surety as soon as the tenant is behind and was reminded without success (Art. 496 OR).
- Rights stay. A surety cannot give up the protections of the law in advance, unless the law allows it (Art. 492 para. 4 OR).
What to do, step by step
- Ask the agency which form it accepts.
- Tell your helper the difference: a co-tenant owes the full rent, a surety owes up to a ceiling.
- For a surety above CHF 2,000, book a notary and bring the spouse's written consent.
- Expect questions. The landlord may ask a person who stands surety for name, date of birth, address, income and pending debt enforcements (FDPIC leaflet, 2025).
- Keep the deposit apart. For a home it is at most three monthly rents, paid into a bank account in the tenant's name (Art. 257e OR).
Where aptari comes in
aptari does not arrange a second signer. It helps you see when you need one. The Match Score from 0 to 100 compares your income with each listing's rent, by fixed rules, with the facts shown. It measures fit, not your chance. Students and newcomers can state in the cover letter, drafted from the dossier on Pro and Ultra, that a parent or employer stands behind the rent.
This is general information, not legal advice.