Mortgage Approval 101: GDS & TDS Explained

Wyatt Tunnicliffe • February 18, 2026

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.


Wyatt Tunnicliffe

Mortgage Broker

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How to Maximize Your Mortgage Renewal Opportunity

By Wyatt Tunnicliffe • August 12, 2026
Your Lender Is Not Obligated to Renew Your Mortgage Many homeowners assume that if they’ve made every mortgage payment on time, their lender is automatically required to renew their mortgage at the end of the term. That’s a common belief—but it isn’t true. When you sign a mortgage, you’re agreeing to a contract for a specific term . Once that term ends, the lender has the legal right to either renew the mortgage or call the loan . There is no obligation to offer a renewal. In practice, most lenders do renew mortgages—but certain situations can prevent that from happening. Reasons a Lender May Decline to Renew A lender may choose not to renew if: Mortgage payments were missed during the term A bankruptcy or consumer proposal has occurred There is a separation or divorce Employment or income has changed A borrower on the mortgage has passed away The lender no longer prefers the property’s location or market The lender is no longer licensed to lend in Canada Even one of these factors can change how a lender views the risk. Why This Matters Because renewal is not guaranteed, waiting until the last minute can put you in a difficult position. Understanding this reality early gives you time and control. How to Protect Yourself at Renewal The best approach is to be proactive. Ideally, you should begin reviewing your options 120 days before your mortgage term ends . This gives you enough time to explore alternatives and make informed decisions—rather than reacting under pressure. Even if your current lender offers a renewal, that’s just one option , not automatically the best one. The lender that was right for you years ago may no longer offer the most competitive rate, terms, or flexibility today. The goal at renewal isn’t convenience—it’s reducing your total cost of borrowing and choosing terms that align with your current situation. Why Work With an Independent Mortgage Professional Working with an independent mortgage professional ensures someone is advocating for you , not the lender. Instead of being limited to one set of products, you can compare options across multiple lenders and choose the solution that best protects your interests. Final Thoughts Whether your lender is offering a renewal or not, the smartest move is to review all your options before signing anything. If your mortgage is coming up for renewal—or if you want to plan ahead—feel free to connect anytime. I’d be happy to help you protect your options and make a confident decision.

How Property Type and Condition Influence Mortgage Financing

By Wyatt Tunnicliffe • August 5, 2026
Why the Property Matters When You’re Qualifying for a Mortgage When qualifying for a mortgage, lenders typically look at four core areas: Income Credit Down payment or equity The property itself Most buyers focus heavily on income, credit, and savings—and for good reason. But even if those boxes are checked, the property can still determine whether a mortgage is approved. Why Lenders Care About the Property From a lender’s perspective, the property is the collateral for the mortgage. In the unlikely event of default, they need to know the home can be sold quickly and at fair market value to recover their funds. Because of this, lenders are careful about the condition, value, and marketability of any property they finance. Homes that are in poor repair, unconventional, or overpriced can raise red flags—even when the borrower is well qualified. Appraisals Are Always Part of the Process Every mortgage requires an appraisal to confirm value. Insured mortgages (through CMHC, Sagen, or Canada Guaranty) often use an automated valuation model completed online. Conventional mortgages typically require a full, on-site appraisal by a certified appraiser. This appraisal is not optional and happens after an offer is accepted—not at the pre-approval stage. Why Pre-Approvals Aren’t a Guarantee A pre-approval is a great first step, but it only assesses you, not the property. Once you’ve made an offer, the lender must approve the specific home you’re buying. Understanding this upfront helps avoid surprises and confusion later in the process. The Risk of Buying Without a Financing Condition In competitive markets, buyers sometimes remove financing conditions to strengthen their offer. However, this comes with risk. If the appraisal comes back low—or the lender is concerned about the property’s condition—you could be denied financing after the offer is firm. In that scenario, your deposit may be at risk. Buying a Home That Needs Work If you’re considering a property that isn’t in perfect condition, there are solutions. A purchase plus improvements program allows you to buy a home and include renovation costs in your mortgage. The process is structured and requires planning, but it can be an excellent way to turn a fixer-upper into a great long-term investment. Final Thoughts Mortgage approval isn’t based solely on your finances—the property matters just as much. Knowing this ahead of time helps you make smarter offers, reduce risk, and plan more effectively. If you’re buying a property that needs work or want clarity on how a lender may view a specific home, feel free to reach out. I’d be happy to walk you through your options and help you plan with confidence.