Mortgage Approval 101: GDS & TDS Explained

Erik Sepper • August 20, 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.


ERIK SEPPER 
MORTGAGE AGENT

CONTACT ME

What Older Canadians Should Know About Mortgage Financing

By Erik Sepper • July 8, 2026
Retirement doesn’t always mean a mortgage-free life anymore. And that’s okay. Between higher home prices, rising living costs, and longer life expectancy, many Canadians are choosing to retire with a mortgage or refinance later in life to create more flexibility. The goal isn’t perfection. It’s having options that actually support the life you want to live. If you’re thinking about how a mortgage fits into your retirement years, you’re not alone—and you’re not out of options. Why work with an independent mortgage professional? Because retirement financing is not one-size-fits-all. Unlike a single bank, an independent mortgage professional can look across multiple lenders and solutions to find what truly fits your income, equity, and long-term plans—not just what one institution offers. Mortgage options available in retirement Traditional Mortgage Solutions Many retirees still qualify for standard mortgages. Pension income, investment income, and other retirement sources can often be used to support an application. If you have good equity and solid credit, this is often the lowest-cost option. Reverse Mortgages For homeowners 55+, a reverse mortgage can unlock tax-free equity from your home with no monthly payments required. There’s no income verification or medical questions, making it a helpful option for those who want to improve cash flow while staying in their home. Home Equity Line of Credit (HELOC) A HELOC allows you to access your home equity as needed and only pay interest on what you use. Many retirees appreciate the flexibility and like consolidating income and expenses in one place. Private Financing Sometimes life throws a curveball. If timing, income, or credit create challenges, private financing can act as a short-term bridge. It’s not usually the first choice, but it can provide solutions when traditional lenders can’t. If you’re approaching retirement—or already there—and wondering how your mortgage fits into the picture, let’s talk. A clear plan can make retirement feel a lot more secure and a lot less stressful.

Why a Mortgage Pre-Approval Protects Both Your Head and Your Heart

By Erik Sepper • July 1, 2026
Why a Mortgage Pre-Approval Protects Both Your Head and Your Heart There’s no denying it—buying a home is an emotional journey. In a competitive market, it can feel like you need to stretch beyond your comfort zone or bid above asking just to have a chance. That pressure can make it hard to separate what you want from what you can realistically afford. One of the biggest pitfalls buyers face is falling in love with a home that’s outside their price range. Once that happens, every other property seems like a compromise—even the ones that might have been a perfect fit otherwise. The best way to avoid this heartache? Get pre-approved before you start shopping. What a Pre-Approval Does for You A mortgage pre-approval gives you more than just a number—it provides clarity, confidence, and protection: Know your buying power : Shop within your true price range and avoid disappointment. Spot potential roadblocks : Uncover issues like credit bureau errors before you make an offer. Get organized : Learn exactly what documentation you’ll need so there are no surprises. Lock in a rate : Many lenders hold your rate for 30–120 days, giving you peace of mind if rates rise. Save yourself heartache : Protect yourself from falling for a home you can’t afford. Head vs. Heart Buying a home is about balance. Your head tells you what’s financially sound, your heart tells you what feels right—and both matter. A pre-approval helps bring those two sides together, so you can make confident choices without emotional stress clouding your judgment. The Bottom Line Looking at properties for fun is one thing—but if you’re serious about buying, a pre-approval is the smartest first step you can take. It sets realistic expectations, saves time, and protects your emotions along the way. If you’d like to explore your options and get pre-approved, I’d be happy to walk through the process with you. Let’s make sure you’re ready to shop with confidence.

Tips to Pay Off Your Mortgage Early

By Erik Sepper • June 24, 2026
Owning a home feels great—carrying a large mortgage, not so much. The good news? With the right strategies, you can shorten your amortization, save thousands in interest, and become mortgage-free sooner than you think. Here are four proven ways to make it happen: 1. Switch to Accelerated Payments One of the simplest ways to reduce your mortgage faster is by moving from monthly payments to accelerated bi-weekly payments . Instead of 12 monthly payments a year, you’ll make 26 half-payments. That works out to the equivalent of one extra monthly payment each year, shaving years off your mortgage—often without you noticing much difference in your budget. 2. Increase Your Regular Payments Most mortgages allow you to boost your regular payment by 10–25%. Some even let you double up payments occasionally. Every extra dollar goes directly toward your principal, which means less interest and faster progress toward paying off your balance. 3. Make Lump-Sum Payments Depending on your lender, you may be able to make lump-sum payments of 10–25% of your original mortgage balance each year. This option is ideal if you receive a bonus, inheritance, or other windfall. Applying a lump sum directly to your principal immediately reduces the interest charged for the rest of your term. 4. Review Your Mortgage Annually It’s easy to put your mortgage on auto-pilot, but a yearly review keeps you in control. By sitting down with an independent mortgage professional, you can check if refinancing, restructuring, or adjusting terms could save you money. A quick annual review helps ensure your mortgage is always working for you—not against you. The Bottom Line Paying off your mortgage early doesn’t require a massive lifestyle change—it’s about making smart, consistent choices. Whether it’s accelerated payments, lump sums, or regular reviews, every step you take helps reduce your debt faster. If you’d like to explore strategies tailored to your situation—or want a free annual mortgage review—let’s connect. I’d be happy to help you find the fastest path to mortgage freedom.