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A co-signer — also called a co-borrower — is added directly to a mortgage application and the property’s title, sharing both ownership and full responsibility for repayment. Unlike a guarantor, a co-signer has an equity stake in the home.
A co-signer’s income and debts are fully included in the GDS and TDS calculations, and because they’re registered on title, they also share in any equity the property builds. This is different from a guarantor, who backstops the debt without any ownership stake.
Families often add a co-signer — a parent helping an adult child, or partners buying together — when one applicant’s qualifying income alone isn’t enough to carry the mortgage. Both co-signers are equally and fully liable for the entire debt, not just their proportional share, if payments are missed.
On title, not just on the hook: a co-signer is registered as a legal owner of the property, unlike a guarantor.
Fully counted in the ratios: a co-signer’s income and debts are added into GDS and TDS for the whole application.
Jointly and fully liable: each co-signer is responsible for the entire mortgage debt, not a percentage of it, if the other stops paying.
Common across the market: used by mortgage agents, submortgage brokers, mortgage associates, and courtiers hypothécaires nationwide to help a borrower reach the qualifying income needed.
Definitions reflect Canadian federal and provincial rules as of the “Updated” date above. Not advice for any specific file.
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