Answers › Buying With a Family Member
If my parents co-sign, will it affect their own borrowing ability?
Answered by Rajiv Verma, Mortgage Broker · Reviewed 18 August 2026 · About a 3 minute read
The direct answer
Yes, it can. Even if you make every payment, your parents remain legally responsible for that debt — and when they apply for another mortgage, loan or line of credit, the new lender may count the obligation when working out what they can borrow. Before anyone co-signs, look past today’s approval: their future plans, their retirement income, and whether they may need to borrow for themselves.
THE SHORT VERSION
- The debt is theirs too, whoever pays it
- A new lender may count the full payment against them
- It can reduce what they qualify for — sometimes materially
- Your perfect payment record doesn’t remove the obligation
- Think about their next five years, not just your next thirty days
Why a perfect payment history isn’t the point
People assume that if the mortgage is never late, it doesn’t count against the co-signer. The obligation exists regardless of how well it’s being serviced.
When your parents apply for something themselves, an underwriter sees a mortgage they’re liable for. Some lenders will exclude it where there’s a clear record of someone else paying — but that’s a lender-by-lender decision, not a rule, and it’s not something to count on.
Where it actually bites
- Downsizing or buying a retirement property — the classic case, and the one people don’t see coming
- Refinancing their own home to help with renovations or to release equity
- Helping another child later — capacity used once may not be available twice
- A credit line or car loan, where the reduced room shows up quietly
- Retirement itself — income usually falls, so an obligation that fitted comfortably at 58 may not at 68
The conversation worth having is about them, not you. Not “can they co-sign” — they usually can. But “what do they want to do in the next five years, and does this get in the way?” That question is rarely asked, and it’s the one that causes the regret.
How to limit the impact
Check whether you need them at all. If a gift would close the gap, they take on nothing.
Borrow less. A smaller mortgage may qualify on your income alone, which removes the question entirely.
Set an exit date. Agree a point — often two or three years — at which you refinance and release them, and be honest about whether you’ll qualify by then.
Have them check their own position first. If they’re planning anything themselves, worth knowing what co-signing costs them before rather than after.
When it’s the wrong move
When they’re close to retirement and may need to borrow. Reduced income plus an added obligation is a hard combination to reverse.
When there’s no realistic path to releasing them. If you won’t qualify alone in a few years, they’re committed indefinitely.
When they haven’t been told plainly what it means. Agreeing to help is not the same as understanding what a co-signer actually is.
What to do next
Bring them into the conversation. I’ll walk through what co-signing commits them to, what it does to their own borrowing, and how and when it ends.
If a gift would do the job instead, I’ll say so — it’s the smaller ask and usually the better one.
Related questions
- What’s the difference between a co-signer and a co-borrower?
- My parents want to help me buy. Do they have to be on the mortgage?
- Should I choose a fixed or variable rate at renewal?
Answered by Rajiv Verma, Mortgage Broker · Mortgage Architects — FSRA Brokerage Licence #12728 · Licensed in Ontario · Office 289.505.0631 · Direct 647.291.7116
General information about Ontario mortgages — not financial, legal or tax advice. How lenders treat co-signed obligations varies and changes. Every file is reviewed individually.