co-signer
US /ˈkoʊˌsaɪ.nɚ/
UK /ˈkoʊˌsaɪ.nɚ/

1.
поручитель, соподписант
a person who signs a document, especially a loan agreement, jointly with another person or persons, and thereby guarantees payment or performance
:
•
My parents had to be a co-signer for my first apartment lease.
Мои родители должны были быть поручителями по моему первому договору аренды квартиры.
•
Without a co-signer, I wouldn't have been approved for the car loan.
Без поручителя мне бы не одобрили автокредит.