Mortgage Approval 101: GDS & TDS Explained

Shawn Johnson • November 19, 2025

Can You Afford That Mortgage? Let’s Talk About Debt Service Ratios

One of the biggest factors lenders look at when deciding whether you qualify for a mortgage is something called your debt service ratios. It’s a financial check-up to make sure you can handle the payments—not just for your new home, but for everything else you owe as well.


If you’d rather skip the math and have someone walk through this with you, that’s what I’m here for. But if you like to understand how things work behind the scenes, keep reading. We’re going to break down what these ratios are, how to calculate them, and why they matter when it comes to getting approved.


What Are Debt Service Ratios?

Debt service ratios measure your ability to manage your financial obligations based on your income. There are two key ratios lenders care about:

  1. Gross Debt Service (GDS)
    This looks at the percentage of your income that would go toward housing expenses only.

   2. Total Debt Service (TDS)
       This includes your housing costs plus all other debt payments—car loans, credit cards, student loans, support payments, etc.


How to Calculate GDS and TDS

Let’s break down the formulas.


GDS Formula:

(P + I + T + H + Condo Fees*) ÷ Gross Monthly Income


Where:

P = Principal

I = Interest

T = Property Taxes

H = Heat


Condo fees are usually calculated at 50% of the total amount


TDS Formula:

(GDS + Monthly Debt Payments) ÷ Gross Monthly Income


These ratios tell lenders if your budget is already stretched too thin—or if you’ve got room to safely take on a mortgage.


How High Is Too High?


Most lenders follow maximum thresholds, especially for insured (high-ratio) mortgages.

As of now, those limits are typically:

GDS: Max 39%

TDS: Max 44%


Go above those numbers and your application could be declined, regardless of how confident you feel about your ability to manage the payments.


Real-World Example

Let’s say you’re earning $90,000 a year, or $7,500 a month.

You find a home you love, and the monthly housing costs (mortgage payment, property tax, heat) total $1,700/month.


GDS = $1,700 ÷ $7,500 = 22.7%


You’re well under the 39% cap—so far, so good.


Now factor in your other monthly obligations:

  • Car loan: $300
  • Child support: $500
  • Credit card/line of credit payments: $700
    Total other debt = $1,500/month


Now add that to the $1,700 in housing costs:
TDS = $3,200 ÷ $7,500 = 42.7%


Uh oh. Even though your GDS looks great, your TDS is just over the 42% limit. That could put your mortgage approval at risk—even if you’re paying similar or higher rent now.


What Can You Do?

In cases like this, small adjustments can make a big difference:

  • Consolidate or restructure your debts to lower monthly payments
  • Reallocate part of your down payment to reduce high-interest debt
  • Add a co-applicant to increase qualifying income
  • Wait and build savings or credit strength before applying


This is where working with an experienced mortgage professional pays off. We can look at your entire financial picture and help you make strategic moves to qualify confidently.


Don’t Leave It to Chance

Everyone’s situation is different, and debt service ratios aren’t something you want to guess at. The earlier you start the conversation, the more time you’ll have to improve your numbers and boost your chances of approval.


If you're wondering how much home you can afford—or want help analyzing your own GDS and TDS—let’s connect. I’d be happy to walk through your numbers and help you build a solid mortgage strategy.


Shawn Johnson

Senior Mortgage Specialist

How Your Credit Score Impacts Mortgage Rates and Approval

By Shawn Johnson • September 9, 2026
What Lenders Mean by “Good Credit” When You Apply for a Mortgage Credit is simply the ability to borrow money today based on the trust that you’ll repay it in the future. When you apply for a mortgage, lenders want proof that you’ve consistently honoured that trust by managing credit responsibly. But what does a good credit history actually look like to a lender? The 2 / 2 / 2 Rule Explained If you’re newer to credit or want a simple way to remember minimum mortgage credit requirements, think of the 2 / 2 / 2 rule: 2 active trade lines Established for at least 2 years With a minimum combined limit of $2,000 This is a common baseline lenders use when assessing credit for mortgage financing. What Counts as a Trade Line? A trade line is any account where credit is extended to you, such as: A credit card A line of credit A car loan A personal or installment loan Each trade line reports your payment history to the credit bureau and contributes to your credit score. For a trade line to be considered active , it must: Have been used at least once, and Show activity at least once every three months Why Time Matters Lenders want to see that you’ve managed credit responsibly over time , not just recently. Using two trade lines consistently for at least two years helps demonstrate stable financial habits and reliability. Understanding Credit Limits vs. Balances The credit limit is what matters—not the balance. For example: A $1,000 credit card + a $2,500 line of credit = $3,500 total limit This meets the minimum requirement You do not need to carry a balance to build credit. In fact, the best approach is to: Use your credit regularly Pay it off in full each month (for credit cards) Make all loan payments on time If your lender offers a credit limit increase and you’re managing credit well, it’s often a good idea to accept it. Higher limits—used responsibly—can strengthen your credit profile. A Simple Way to Build Credit Automatically One effective strategy is to: Put recurring bills on your credit card Set up an automatic transfer to pay the balance in full every month Automation helps build positive credit history without requiring constant attention—just be sure to monitor your accounts to ensure everything runs smoothly. What About Credit Scores? Yes, credit scores matter—but they’re not the whole story. If you: Have two active trade lines Established for two years With at least $2,000 in total limits And no missed payments …your credit score will generally take care of itself. That said, it’s still wise to review your credit report occasionally to check for errors or unfamiliar accounts. Final Thoughts If you’re thinking about buying a home in the next couple of years, now is the perfect time to review your credit and make sure you’re on track. Small adjustments today can make a big difference when it’s time to apply for a mortgage. If you’d like help reviewing your credit or understanding how it affects your mortgage options, feel free to connect anytime. I’d be happy to walk through it with you and help you plan with confidence.

Bank of Canada Holds Rate at 2.25% — September 2, 2026

By Shawn Johnson • September 2, 2026
The Bank of Canada announced today that it is holding its target for the overnight rate at 2.25%, with the Bank Rate at 2.5% and the deposit rate at 2.20%. While Canada's economic recovery is broadening, a new layer of uncertainty has entered the picture. Here is what happened and what it means for your mortgage.