Lease dictionary
Guarantor (co-signer)
Someone who promises to pay your rent if you don't - often a parent or relative.
A guarantor (or co-signer) signs the lease promising to cover rent and damages if you can't. Landlords commonly require one when income is under a multiple of rent (often 2.5–3×) or credit history is thin.
The guarantee often covers the entire lease - including renewals and your roommates' share under joint and several liability - unless it's expressly limited.
Watch out
Guarantors: ask for a cap (e.g. rent only, not damages) and a term limit. An open-ended guarantee can outlive the first lease year.
See it in action
The Rent affordability calculator puts this term to work for you.