Calculators
Niagara Mortgage Affordability & Stress Test Calculator
Enter your household income, monthly debts and down payment to see the most a lender is likely to approve at the stress-test rate, with property tax for the Niagara municipality you choose.
Reviewed November 13, 2026 · Indicative figures, OAC
What this calculator shows
Lenders do not approve you at the rate you will pay. Federally regulated lenders qualify you at a higher stress-test rate, then check two ratios against your gross income. Because property tax sits inside both ratios, the same household can afford a noticeably different price in Fort Erie than in Grimsby. This calculator runs that test the way an underwriter does and returns a maximum purchase price and mortgage for the municipality you pick.
- Minimum qualifying rate
- 5.25% or rate + 2%
- GDS limit (insured)
- 39%
- TDS limit (insured)
- 44%
- Qualifying rate at a 4.29% contract
- 6.29%
The inputs
- Municipality. Sets the approximate effective residential tax rate used to estimate property tax at each price tested.
- Gross household income. Before tax, for everyone who will be on the mortgage. Self-employed income is usually the two-year average of line 15000 of your tax return, with some add-backs.
- Monthly debt payments. Car loans, student loans, support payments, plus 3% of each credit card balance and a qualifying payment on lines of credit.
- Down payment. Savings, gifts, RRSP Home Buyers' Plan or FHSA funds.
- Rate and amortization. Your expected contract rate and 25 or 30 years.
How the numbers are calculated
Qualifying rate
Qualifying rate = the higher of 5.25% or (contract rate + 2.00%). This is the OSFI B-20 minimum qualifying rate and applies at federally regulated lenders on purchases and refinances. All insured mortgages are tested this way.
The two ratios
GDS = (principal and interest at the qualifying rate + property tax + heating + 50% of condo fees) ÷ gross monthly income.
TDS = (all GDS costs + all other monthly debt payments) ÷ gross monthly income.
On an insured file the limits are GDS ≤ 39% and TDS ≤ 44%, with at least one borrower holding a credit score of 600 or more.
Finding the maximum
For each candidate price the calculator works out the mortgage (price − down payment), adds the default insurance premium if the down payment is under 20%, computes the payment at the qualifying rate with semi-annual compounding (i = (1 + r/2)1/6 − 1; payment = P × i ÷ (1 − (1 + i)−n)), adds property tax (price × town rate ÷ 12) and $125 a month for heat, and checks both ratios. The highest price that passes both, and that your down payment covers at the federal minimum, is the result.
Worked example: $110,000 household in St. Catharines
A couple earns $110,000 a year ($9,166.67 a month), has a $450 car payment, $50,000 saved and an indicative insured 5-year fixed rate of 4.29% over 25 years. The qualifying rate is 6.29%. The calculator lands at a price of about $484,000:
| Line | Calculation | Amount |
|---|---|---|
| Purchase price | highest passing price | $484,000 |
| Base loan (89.67% LTV) | $484,000 − $50,000 | $434,000 |
| Premium at 3.10% | $434,000 × 3.10% | $13,454 |
| Insured mortgage | $434,000 + $13,454 | $447,454 |
| Payment at 6.29% (qualifying) | 300 months | $2,940.42 |
| Property tax | $484,000 × 1.26% ÷ 12 | $508.20 |
| Heating | standard estimate | $125.00 |
| GDS | $3,573.62 ÷ $9,166.67 | 38.98% |
| TDS | ($3,573.62 + $450) ÷ $9,166.67 | 43.89% |
| Actual payment at 4.29% | what you would pay | $2,424.57 |
Both ratios sit just under their limits, so this is the ceiling. The real payment is about $516 a month lower than the qualifying payment; that gap is the cushion the stress test is designed to build in.
Same household, different town
Keep every input the same and change only the municipality. The approximate tax rate moves the maximum price:
| Municipality | Approx. tax rate | Maximum price |
|---|---|---|
| Grimsby | 1.15% | $489,500 |
| St. Catharines | 1.26% | $484,000 |
| Welland | 1.32% | $481,000 |
| Fort Erie | 1.68% | $463,000 |
That is a $26,500 difference between Grimsby and Fort Erie on identical income, debt and savings. Tax rates are approximate; confirm with the municipality's current tax rates.
What the stress test costs you, in dollars
Take the same household with $150,000 down, buying with no default insurance in St. Catharines. Qualified at 6.39% (an insurable 4.39% rate + 2.00%), the maximum price is about $578,500 on a $428,500 mortgage. If a lender qualified the same file at a 4.69% contract rate, the ceiling would be about $642,000 on a $492,000 mortgage. This is an illustration of the mechanics, not a statement of any one credit union's policy: products, ratios and rates vary, and every file is on approved credit. A lower qualifying rate also means a thinner cushion if rates rise at renewal.
Limitations
- Lenders may count debts differently, especially lines of credit and student loans.
- Rental, bonus, commission, tipped and self-employed income are often averaged or discounted.
- Condo fees are not included unless you add them; 50% of the fee counts in GDS.
- Default insurers and lenders can set stricter limits based on credit score.
Once you have a target price, run it through the payment and closing cost calculator to see the cash you need on closing. The ratio rules are explained in depth in our stress test and GDS/TDS guide, and the lender differences in monoline vs credit union.
Next steps
- Clean up the TDS. Paying down a card balance cuts its counted payment by 3% of the amount repaid.
- Test two or three towns. Tax alone can move your ceiling by tens of thousands of dollars.
- Get it underwritten. Send your numbers through the pre-approval page so a licensed agent can confirm them with real lender criteria.
Frequently asked questions
What rate do I have to qualify at in 2026?
At a federally regulated lender you qualify at the higher of 5.25% or your contract rate plus 2.00%. With a 4.29% insured 5-year fixed, the qualifying rate is 6.29%; with a 3.65% variable, it is 5.65%.
What are GDS and TDS limits on an insured mortgage?
Gross debt service, your housing costs divided by gross monthly income, can be up to 39%. Total debt service, housing costs plus all other debt payments, can be up to 44%. At least one borrower needs a credit score of 600 or more.
How are credit cards counted?
Lenders typically count 3% of the outstanding balance as a monthly payment, whatever your actual minimum is. A $10,000 balance adds $300 a month to your TDS, even if you pay it in full each month.
Why does my town change how much I can borrow?
Property tax is part of both GDS and TDS. Approximate effective rates in Niagara range from about 1.08% in Niagara-on-the-Lake to about 1.68% in Fort Erie. For a $110,000 household with $50,000 down, that difference moves the maximum price from about $489,500 in Grimsby to about $463,000 in Fort Erie.
Can a credit union approve me without the stress test?
Ontario credit unions are not bound by OSFI B-20, so some offer uninsured mortgages qualified at the contract rate or with extended ratios on certain products. You generally need 20% or more down, and policies change, so a broker checks current criteria for your file.
Pre-approval & rate review
Get your Niagara mortgage numbers checked
Tell us where you are buying or what you owe. We reply by email, usually within one business day, with options from across the lender tiers.
- A licensed advisor reviews your numbers against A-lenders, Ontario credit unions and alternative lenders.
- Rate holds of up to 120 days on purchases and renewals (lender-dependent).
- On prime files the lender pays the brokerage, so there is no fee to you; any fee on alternative or private files is disclosed in writing first.
- Nothing goes to a lender or credit bureau until you say so.
Prefer email? Write to hello@mortgageniagara.com.