How Student Debt Affects Mortgage Qualification
Lenders use two debt service ratios to determine affordability:
| Ratio | Maximum | What It Includes | Student Loan Impact |
|---|---|---|---|
| GDS (Gross Debt Service) | 39% | Mortgage + property tax + heating + 50% condo fees | Not directly included |
| TDS (Total Debt Service) | 44% | GDS + all other debts | Student loan payment counted here |
If your housing costs already use the full GDS limit, the gap between GDS (39%) and TDS (44%) leaves just 5% of gross income for all non-housing debts, including student loans, car payments and credit card minimums.
How much a loan payment costs you in mortgage
When your total debt service ratio is the limit, each dollar of monthly debt payment is a dollar less mortgage payment you qualify for. At a 6.99% qualifying rate over 25 years (semi-annual compounding), each $100 a month of student loan payments removes about $14,300 of mortgage; at a 5.25% qualifying rate, about $16,800.
| Monthly student loan payment | Mortgage you no longer qualify for (6.99% qualifying rate) |
|---|---|
| $300 | about $42,900 |
| $500 | about $71,400 |
If your GDS ratio is the tighter limit, the loan payment may cost you less, or nothing. The mortgage affordability calculator works it out with your own debts.
Strategies to Buy a Home with Student Debt
Strategy 1: Optimize Your Debt Payments Before Applying
| Action | Impact on TDS Ratio |
|---|---|
| Extend repayment (up to 14.5 years) | On an interest-free federal loan, stretching 114 months to 174 months lowers the payment by about a third |
| Pay off highest-payment debt first | Directly reduces TDS |
| Refinance a provincial or private loan that charges interest | May reduce the monthly payment (the federal part has no interest to save) |
Strategy 2: Choose a repayment schedule
| Repayment Plan | Monthly Payment | Impact on Mortgage Qualification |
|---|---|---|
| Standard (9.5 years) | $400 (example) | Higher payment weighs more on TDS |
| Extended (14.5 years) | $262 on the same interest-free balance | Lower payment weighs less on TDS |
| RAP (Repayment Assistance Plan) | Based on your income, can be $0 | Very low payment; lender may question stability |
Important: Lenders will use your actual monthly payment amount for TDS calculations. If your RAP payment is $0, some lenders may still impute a payment amount.
Strategy 3: Increase Your Income
At a 6.99% qualifying rate, each extra $10,000 of income supports roughly $46,000 more mortgage (at the housing cost limit):
Ways people raise qualifying income include a raise or new job, a side business (lenders look for a track record before counting self-employment income) and rental income from a suite in the home (see buying as a single person for how CMHC counts it).
Strategy 4: Save a Larger Down Payment
| Down Payment | Monthly Savings | Impact |
|---|---|---|
| 5% on $400K = $20,000 | Minimum required | Insurance premium at 4.00% of $380,000 = $15,200 |
| 10% on $400K = $40,000 | Lower insurance premium | Premium at 3.10% of $360,000 = $11,160 |
| 20% on $400K = $80,000 | No mortgage default insurance | No premium, and a smaller mortgage |
Strategy 5: Leverage First-Time Buyer Programs
| Program | Max Benefit | How It Helps |
|---|---|---|
| FHSA | $40,000 of deductible contributions | Tax-free growth and withdrawal for the down payment |
| Home Buyers’ Plan (HBP) | $60,000 RRSP withdrawal | With the FHSA, up to $100,000 plus growth |
| Home buyers’ amount | $10,000 credit claim | Lowers your tax for the year you buy |
Should You Pay Off Student Debt or Buy a Home?
Signs that paying down debt first may fit
| Situation | Reasoning |
|---|---|
| TDS ratio exceeds 44% | You won’t qualify for a mortgage until debt is reduced |
| Your loan charges a high interest rate | Paying it off gives a guaranteed return |
| The monthly payment is large | It competes with housing costs for cash flow |
| Job stability is uncertain | Carrying both debts is risky without stable income |
Signs that buying first may fit
| Situation | Reasoning |
|---|---|
| TDS ratio is within limits | You can qualify with the loan in place |
| Your loan is interest-free or low-rate | The loan costs little to carry while you build equity |
| Rent is close to the cost of owning | Part of each mortgage payment builds equity instead |
| Down payment is ready | The main remaining question is whether the monthly costs fit |
Whether paying off the loan first or buying first leaves you better off depends on your loan’s interest rate (federal student loans no longer charge interest), how home prices move while you wait, and how much rent you pay meanwhile. Paying off debt vs saving for a house walks through the trade-off.
Mortgage Lender Tips for Student Debt Borrowers
| Tip | Details |
|---|---|
| Get a mortgage broker | Brokers can find lenders with the most flexible TDS calculations |
| Provide a letter of employment | Strong job letter helps offset debt concerns |
| Show savings history | Regular savings deposits demonstrate financial discipline |
| Pay down credit cards first | Credit card minimums count in TDS and carry higher interest |
| Don’t take on new debt | Avoid car loans or new credit cards before applying |
Student loan interest
Since April 1, 2023, the federal part of Canada Student Loans doesn’t charge interest. Provincial loans follow their own rules; see the student loans hub for your province.
Related Articles
Sources
The figures and rules on this page come from these sources, last checked against them between August 29, 2026 and September 28, 2026. How we check facts.
- Canada Revenue Agency: FHSA: Participating in your FHSAs
- Canada Revenue Agency: RRSP: The Home Buyers' Plan
- Canada Revenue Agency: RRSP: How to participate in the Home Buyers' Plan
- Canada Revenue Agency: Line 31270 – Home buyers' amount
- CMHC: Calculating GDS / TDS
- CMHC: CMHC Purchase
- CMHC: Home Start
- Employment and Social Development Canada: Canada Student Financial Assistance Program annual report 2023 to 2024
- Justice Laws (Canada): Bank Act
- OSFI: Minimum qualifying rate for uninsured mortgages