Quebec Mortgage Payment: The Calculation Your Bank Doesn't Show You
When you shop for a mortgage in Quebec, your bank shows you a single number: the monthly payment. But that number hides a very specific mechanism — and several costs nobody ever breaks down for you. Semi-annual compounding, mortgage default insurance premiums, QST on that premium payable in cash, welcome tax: here is the full calculation your bank doesn't show you.
1. The Canadian quirk: your rate compounds twice a year
This is the first thing American calculators (and several online simulators) get wrong: in Canada, a fixed-rate mortgage is not compounded monthly. The Canadian convention, which lenders are required to use, is that interest is compounded semi-annually, not in advance. You can't just divide your annual rate by 12.
The effective monthly rate is calculated like this:
monthly rate = (1 + annual rate / 2)^(1/6) − 1
With a nominal rate of 5.25%, that gives a monthly rate of 0.4328% — slightly less than 5.25% / 12 = 0.4375%. The gap looks tiny, but it changes the payment by a few dollars a month, which adds up to thousands of dollars over 25 years. To double-check your own numbers, [our mortgage calculator](/en/quebec-mortgage-calculator) applies exactly this Canadian convention, with the CMHC premium and welcome tax built in.
2. The CMHC premium: the invisible cost added to your loan
If your down payment is less than 20% of the purchase price, your loan must be insured against default — through CMHC, Sagen or Canada Guaranty, whichever your lender picks. This insurance protects the lender, not you, but you pay the premium. The good news: it's almost always added to the loan balance rather than paid upfront.
The premium rate depends on your loan-to-value ratio (the loan divided by the purchase price), according to CMHC's official schedule:
| Down payment | Loan-to-value ratio | Premium rate |
|---|---|---|
| 5% (minimum) | 90.01% to 95% | 4.00% |
| 10% | 85.01% to 90% | 3.10% |
| 15% | 80.01% to 85% | 2.80% |
| 20% and up | 80% or less | no premium |
Two important details. First, if you're a first-time buyer (or buying a newly built home), you can amortize over 30 years instead of 25 — but a 0.20% surcharge is then added to the rates above. Second, since December 15, 2024, the maximum insurable price rose from $1M to $1.5M: you can now buy with less than 20% down on a property worth up to $1.5M.
3. QST on the premium: nearly $1,900 in cash on closing day
Here's the cost almost everyone forgets to budget: in Quebec, QST at 9.975% applies to the mortgage insurance premium. And unlike the premium itself, this tax cannot be added to the loan — CMHC states this explicitly. It's payable in cash at the notary's office, alongside your other closing costs.
Back to our example: a $500,000 home bought with a 5% down payment ($25,000). The base loan is $475,000, the 4.00% premium is $19,000, so your actual loan from day one is $494,000. The QST on the premium: $19,000 × 9.975% = $1,895.25 out of your pocket on signing day. If you hadn't planned for it, that's a nasty surprise.
4. The real cash needed on closing day: down payment + taxes + fees
The monthly payment is only part of the equation. On signing day at the notary, you also pay in cash: the QST on the premium ($1,895.25 in our example), the welcome tax (land transfer duties, calculated in brackets on the purchase price), notary fees and property tax adjustments. To estimate the welcome tax in your municipality, [our welcome tax calculator](/en/quebec-welcome-tax-calculator) applies the bracket schedule, including Montreal's higher brackets.
5. Full worked example: $500,000, 5% down, 5.25% over 25 years
Putting it all together with a 5.25% nominal rate compounded semi-annually:
- Purchase price: $500,000
- Down payment (5%): $25,000
- Base loan: $475,000
- CMHC premium (4.00%): $19,000
- Total loan from day one: $494,000
- QST on the premium (cash): $1,895.25
- Effective monthly rate: 0.4328%
- Monthly payment: $2,943.84
The very first payment tells the story: $2,137.98 in interest and only $805.85 in principal. After one year, you've paid $35,326.08 but your balance has only dropped by $9,903.75 (balance: $484,096.25) — the rest, $25,422.27, went to interest. That's normal: at the start of an amortization, interest always dominates.
Here's how the balance evolves over 25 years:
| Year | Remaining balance | Interest that year | Cumulative interest |
|---|---|---|---|
| 1 | $484,096.25 | $25,422.27 | $25,422.27 |
| 5 | $438,925.80 | $23,141.03 | $121,555.90 |
| 10 | $367,561.68 | $19,536.94 | $226,821.88 |
| 15 | $275,089.38 | $14,866.82 | $310,979.69 |
| 20 | $155,265.52 | $8,815.37 | $367,785.92 |
| 25 | $0 | $974.02 | $389,150.50 |
Total paid over 25 years: $883,150.50, including $389,150.50 in interest. In other words, the $500,000 home will have cost you $883,150.50 in payments — not counting the down payment or taxes.
6. 5%, 10% or 20%: what the down payment really changes
| Down payment | CMHC premium | Total loan | Monthly payment | Interest over 25 years |
|---|---|---|---|---|
| 5% ($25,000) | $19,000 | $494,000 | $2,943.84 | $389,150.50 |
| 10% ($50,000) | $13,950 | $463,950 | $2,764.76 | $365,478.49 |
| 20% ($100,000) | $0 | $400,000 | $2,383.67 | $315,101.62 |
Moving from 5% to 20% down saves $560.16 a month and $74,048.88 in interest over 25 years. Between 5% and 10%, the gap is $179.08 a month. To see where you stand with your own budget, [our down payment calculator](/en/quebec-down-payment-calculator) breaks down the premium, the 9.975% tax and the cash required.
7. The levers your bank rarely mentions
Accelerated bi-weekly payments. Instead of $2,943.84 a month, you pay $1,471.92 every two weeks — the equivalent of one extra monthly payment per year. The result on our example: the loan is paid off in 21.4 years instead of 25, saving nearly 4 years of interest.
30-year amortization for first-time buyers. Your monthly payment drops to about $2,715.83, but the premium rises to 4.20% (the 0.20% surcharge) and you pay $482,749.48 in total interest — nearly $93,600 more than over 25 years. Useful for passing the stress test at purchase time, expensive over the long run.
The guide to saving your down payment. If your goal is to move from 5% to 10% or 20%, our [RRSP and FHSA guide](/en/blog/rrsp-fhsa) explains how to combine both plans to grow your down payment tax-sheltered.
The bottom line
Your mortgage payment isn't a magic number pulled from a hat: it's the result of a precise formula (Canadian semi-annual compounding), inflated by an insurance premium based on your loan-to-value ratio — itself taxed at 9.975%, payable in cash. Understanding each layer puts you back in control: choosing your down payment with full knowledge, budgeting the real cash needed on closing day, and using the right repayment levers. Run your own numbers with [our mortgage calculator](/en/quebec-mortgage-calculator) — free, and no bank appointment required.
Frequently asked questions
Why is my payment different from "annual rate divided by 12"?
Because in Canada, fixed-rate mortgages are compounded semi-annually, not in advance. The effective monthly rate is (1 + annual rate / 2)^(1/6) − 1, slightly lower than the rate divided by 12. At 5.25%, that's 0.4328% per month instead of 0.4375%.
Is mortgage default insurance (CMHC) mandatory?
Yes, whenever your down payment is less than 20% of the purchase price. The rate ranges from 2.80% to 4.00% of the loan amount depending on your loan-to-value ratio. With 20% or more down, no premium is charged.
Can I roll the QST on the CMHC premium into my mortgage?
No. In Quebec, the 9.975% QST charged on the premium cannot be financed: it's payable in cash at the notary. On a $19,000 premium, that's $1,895.25 to budget for at closing.
Is the 30-year amortization for first-time buyers worth it?
It lowers the monthly payment (about $2,715.83 instead of $2,943.84 in our example), but the premium rises to 4.20% and you pay nearly $93,600 more in total interest. It's a tool for passing the stress test, not a saving.
Do accelerated bi-weekly payments really make a difference?
Yes: $1,471.92 every two weeks equals one extra monthly payment per year. On our $494,000 example at 5.25%, the loan is paid off in 21.4 years instead of 25 — nearly 4 years of interest saved.
Official sources
- SCHL — Primes d'assurance prêt hypothécaire (barème officiel)
- CMHC — Mortgage Loan Insurance: Premium Information (official schedule)
- Banque Scotia — Prêts hypothécaires à taux fixe (taux calculés semestriellement, et non d'avance)
- Ministère des Finances Canada — Réformes hypothécaires (plafond 1,5 M$, amortissement 30 ans)