Buying a Home With Student Debt: How Lenders Really Count Your Loans
If you graduated with a five-figure student loan and a suspicion that homeownership is therefore off the table, here's the useful correction: lenders approve buyers with student debt every single day. What actually matters is not whether you owe, but how the monthly arithmetic of your debt interacts with the mortgage you want — and that arithmetic contains a few rules most borrowers have never heard of.
The Ratios Where Your Student Loan Lives
Mortgage qualification in Canada runs on two ratios. GDS (gross debt service) measures housing costs — stress-tested mortgage payment, property tax, heat, half of condo fees — against gross income, with lenders generally wanting 39% or less. TDS (total debt service) adds every other monthly obligation — car loans, credit card minimums, lines of credit, and student loans — with a ceiling around 44%.
Student debt therefore attacks your approval through the 5-point gap between GDS and TDS. Your housing costs can consume up to 39% of gross income, but only if other debts stay under roughly 5%. A big student loan payment eats that buffer, and then starts eating directly into how much house you qualify for. (Full mechanics in our affordability guide.)
How Lenders Count a Payment That Might Not Exist
Here's where it gets non-obvious. What monthly figure goes into TDS?
If you're actively repaying: generally the actual payment on your statement.
If you're not repaying yet — still in school, in your grace period, or on reduced payments — most lenders don't enter zero. They impute a payment, commonly around 3% of the outstanding balance per month for unsecured debt treatment, though policies vary: some use 1–1.5% for government student loans, others use the payment from your loan documents. On a $40,000 balance, the difference between an imputed 3% ($1,200/month) and an actual repayment plan ($350/month) is enormous — the imputed version can shrink your maximum mortgage by well over $150,000.
The practical move: if your loan is in a non-repayment status, consider formally establishing your repayment schedule before applying, so there's a real, documented payment for the lender to use instead of a punishing imputation. And because policies differ meaningfully between lenders, this is a genuinely good file for a mortgage broker, who will know which lender's student-debt treatment flatters your situation.
Government loans vs. private debt. Canada Student Loans and provincial programs come with flexible, income-tested repayment (the federal Repayment Assistance Plan can reduce payments substantially — and federal loans have carried no interest since 2023). Lenders like the documentation and predictability. A student line of credit from a bank, by contrast, is just revolving debt: expect the ~3%-of-balance treatment, and note that its utilization also affects your credit score in a way a government loan doesn't.
What Student Debt Does to Your Number
A worked example under mid-2026 conditions (low-4s contract rates, stress-tested in the low 6s). Priya earns $80,000, has a $30,000 down payment plus closing costs, no car loan, good credit — and $32,000 of student debt at $380/month.
Without the student loan, her ratios support a mortgage around $375,000. With the $380 payment in TDS, the mortgage room drops to roughly $310,000–$320,000. The rule of thumb hiding in that gap: every $100 of monthly debt payment costs roughly $15,000–$18,000 of mortgage capacity at today's stress-tested rates.
That's the honest damage — real, but bounded. A manageable student payment shifts which home you buy years before it determines whether you buy.
Pay Down the Loan or Save the Down Payment?
The eternal graduate question, and the answer is more mechanical than motivational.
Prioritize the down payment when your student payment is modest and your TDS has room. Down payment dollars do double duty — they shrink the mortgage and can lift you past an insurance-premium tier (or eventually the 20% threshold). And they can work through tax-advantaged accounts on the way: FHSA first, always, for the deduction-in, tax-free-out combination (see our down payment sources guide).
Prioritize the debt when the monthly payment is what's binding your TDS — especially high-rate private debt. Killing a $300/month student line of credit payment adds roughly $45,000–$55,000 of mortgage capacity; it's often the highest-leverage $15,000 a would-be buyer can spend. Zero-interest federal loans, by contrast, are almost never worth prepaying ahead of down-payment savings — their rate costs you nothing; only their payment costs you ratio room.
The blended reality for most: make normal payments on cheap government debt, extinguish expensive private debt, and pour the rest into the FHSA. Model your own version both ways in the affordability calculator — it takes ten minutes and replaces a year of internet debate.
A note on the nuclear option: some buyers consider consolidating student debt into a lower monthly payment to free up TDS. It can work arithmetically, but stretching $30,000 over a longer horizon to buy sooner means paying interest longer — and lenders will still see and count the new payment. Do the honest total-cost math first.
Beyond the Ratios: Credit and Down Payment
Two quieter effects worth knowing. First, your repayment history on student loans reports to the credit bureaus — years of on-time student loan payments are quietly building the credit profile your mortgage application needs. One missed payment does the opposite; automate the payment and never think about it again. Second, student debt makes lenders more interested in the source and stability of everything else in your file: a clean 90-day paper trail on the down payment and stable employment history carry extra weight when your TDS is close to the line. If family help is part of the picture, gifts and co-signing both interact with student-debt files in useful ways.
The Bottom Line
Student debt changes your mortgage math in three specific, calculable ways: it occupies TDS room (about $15,000–$18,000 of mortgage per $100 of monthly payment), it gets imputed harshly when no repayment plan exists, and its private varieties cost more ratio room than its government ones. Every one of those effects has a countermove — document a real repayment plan, kill the expensive debt first, let cheap federal debt ride, and route savings through the FHSA.
Start with thirty honest minutes in the affordability calculator, with your real payments in it. For most graduates, the result isn't "no" — it's a number, a timeline, and a shorter to-do list than the internet suggested. Then plug that number into the first-time buyer roadmap and get moving.