A line of credit with a co-signer is a revolving credit facility approved with a second person as joint borrower, letting you draw, repay, and re-borrow up to a set limit.
A line of credit with a co-signer is a revolving credit facility approved with a second person as joint borrower, letting you draw, repay, and re-borrow up to a set limit. It behaves differently from an installment loan: there is no fixed schedule that pays it off, and the balance can rise again every time you use it. That flexibility is useful, but it also means the co-signer's exposure does not shrink automatically over time the way it would on a term loan.
How a line of credit differs from a loan
An installment loan gives you a lump sum to repay over a fixed term. A line of credit gives you a ceiling you can borrow against as needed, usually at a variable interest rate tied to the lender's prime rate. You pay interest on what you use, and you can repay and re-borrow. The FCAC loans hub explains the difference between secured and unsecured borrowing, and the Bank of Canada publishes interest-rate information that helps explain how variable rates move.
Because the balance is revolving, a line of credit can be harder to clear. Many borrowers pay interest only or make small payments, leaving the principal outstanding for years. For a co-signer, that means the obligation can persist and even grow if the borrower keeps drawing on the account.
Secured and unsecured lines of credit
| Type | How it works | Co-signer exposure |
|---|---|---|
| Unsecured line | No collateral; higher rate | Full balance plus interest, no automatic end date |
| Secured line | Backed by an asset, often a home | Full balance; the asset is also at risk |
| Student line | Often requires a co-signer | Full balance; interest may accrue during study |
| Business line | May need a personal guarantee | Guarantee can reach personal assets |
A secured line is cheaper because the lender has collateral, but the borrower risks the asset. A home-equity line of credit is a common example; see our guide to HELOC with a co-signer for how that product works in Canada.
The co-signer's position on revolving credit
Co-signing a line of credit is a long-term commitment. The Financial Consumer Agency of Canada explains that co-signing makes both parties equally responsible for the unpaid balance, and the New Brunswick Financial and Consumer Services Commission warns that a co-signer may have to repay the full debt plus interest and costs. The Clicklaw Wikibooks notes that the debt can be pursued in court and reported on the co-signer's credit report.
There is an additional wrinkle with revolving credit. Because the borrower can re-draw the limit, the co-signer's exposure can increase without any new signature. Some lenders will reduce or freeze a line if the co-signer asks, but not all will, and not without the borrower's agreement. Anyone co-signing a line of credit should assume the maximum limit is the real exposure, not the current balance.
How to use a co-signed line responsibly
- Treat the limit as a ceiling, not a target. Borrow only what you need and repay regularly.
- Pay more than the interest. Otherwise the principal never falls.
- Keep the utilization low. High utilization affects credit scores for both parties.
- Agree on rules in advance. Decide what the line may be used for and when it will be paid down.
- Plan for release. Ask the lender how the co-signer can be removed once the balance is cleared.
It is also worth knowing the legal ceiling on cost. The federal Criminal Code section 347 sets the criminal interest rate at 35% APR, in force since 1 January 2025. Variable-rate lines move with market rates, so the Bank of Canada is a useful reference for how rates are set.
Common mistakes to avoid
- Paying interest only. The balance never falls and the co-signer stays exposed.
- Using the line for daily spending. A credit line is not a chequing account.
- Assuming the co-signer's risk shrinks. Revolving credit can rise again after repayment.
- Ignoring utilization. Maxing the line hurts both credit scores.
- No release plan. Without one, the co-signer may be tied to the account indefinitely.
Who this suits
A co-signed line of credit suits a borrower with steady income who needs flexible access to funds and has a concrete plan to repay, plus a co-signer who understands the revolving risk. It is a poor fit for someone who would use it to cover a recurring shortfall, or for a co-signer who cannot absorb the maximum limit. The Financial Consumer Agency of Canada explains how utilization affects credit scores, and the Office of Consumer Affairs publishes consumer information.
How lenders set and review a credit limit
A line of credit limit is not fixed forever. Lenders review accounts periodically and may raise or lower the limit based on payment behaviour, credit utilization, income changes, and market conditions. A limit increase sounds helpful, but for a co-signer it means the potential exposure grows without a new signature. A limit decrease can also cause problems if the balance is already high, because the account may be over its limit and incur fees.
Both parties should understand how the lender handles reviews and whether the co-signer is notified of changes. If the goal is to cap the risk, ask whether the limit can be frozen or reduced. The FCAC loans hub explains how lines of credit work, and the Bank of Canada publishes interest-rate information for variable-rate products. Reviewing the account regularly, keeping utilization low, and paying down principal are the practical ways to keep a co-signed line from becoming a long-term burden.
Related reading: our guides to personal loans with a co-signer and installment loans with a co-signer cover the neighbouring products in more detail.
Nothing here is financial or legal advice. Confirm the rate, the limit, and the release terms in writing, and consult a licensed adviser for your own situation.