Mortgage Approval 101: GDS & TDS Explained

Shawn Dreger • December 23, 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 Dreger
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First-Time Buyer? Here’s How to Tell If You’re Ready

By Shawn Dreger • January 13, 2026
Ready to Buy Your First Home? Here’s How to Know for Sure Buying your first home is exciting—but it’s also a major financial decision. So how can you tell if you’re truly ready to take that leap into homeownership? Whether you’re confident or still unsure, these four signs are solid indicators that you’re on the right path: 1. You’ve Got Your Down Payment and Closing Costs in Place To purchase a home in Canada, you’ll need at least 5% of the purchase price as a down payment. In addition, plan for around 1.5% to 2% of the home’s value to cover closing costs like legal fees, insurance, and adjustments. If you’ve managed to save this on your own, that’s a great sign of financial discipline. If you're receiving help from a family member through a gifted down payment , that works too—as long as the paperwork is in order. Either way, having these funds ready shows you’re prepared for the upfront costs of homeownership. 2. Your Credit Profile Tells a Good Story Lenders want to know how you manage debt. Before they approve you for a mortgage, they’ll review your credit history. What they typically like to see: At least two active credit accounts (trade lines) , like a credit card or loan Each with a minimum limit of $2,000 Open and active for at least 2 years Even if your credit isn’t perfect, don’t panic. There may still be options, such as using a co-signer or working on a credit improvement plan with a mortgage expert. 3. Your Income Can Support Homeownership—Comfortably A steady income is essential, but not all income is treated equally. If you’re full-time and past probation , you’re in a strong position. If you’re self-employed, on contract, or rely on variable income like tips or commissions, you’ll generally need a two-year history to qualify. A general rule: housing costs (mortgage, taxes, utilities) should stay under 35% of your gross monthly income . That leaves plenty of room for other living expenses, savings, and—yes—some fun too. 4. You’ve Talked to a Mortgage Professional Let’s be real—there’s a lot of info out there about buying a home. Google searches and TikToks can only take you so far. If you're serious about buying, speaking with a mortgage professional is the most effective next step. Why? Because you'll: Get pre-approved (and know what price range you're working with) Understand your loan options and the qualification process Build a game plan that suits your timeline and financial goals The Bottom Line: Being “ready” to buy a home isn’t just about how much you want it—it’s about being financially prepared, credit-ready, and backed by expert advice. If you’re thinking about homeownership, let’s chat. I’d love to help you understand your options, crunch the numbers, and build a plan that gets you confidently across the finish line—keys in hand.

Everything You Should Know Before Buying a Home

By Shawn Dreger • January 6, 2026
Thinking About Buying a Home? Here’s What to Know Before You Start Whether you're buying your very first home or preparing for your next move, the process can feel overwhelming—especially with so many unknowns. But it doesn’t have to be. With the right guidance and preparation, you can approach your home purchase with clarity and confidence. This article will walk you through a high-level overview of what lenders look for and what you’ll need to consider in the early stages of buying a home. Once you’re ready to move forward with a pre-approval, we’ll dive into the details together. 1. Are You Credit-Ready? One of the first things a lender will evaluate is your credit history. Your credit profile helps determine your risk level—and whether you're likely to repay your mortgage as agreed. To be considered “established,” you’ll need: At least two active credit accounts (like credit cards, loans, or lines of credit) Each with a minimum limit of $2,500 Reporting for at least two years Just as important: your repayment history. Make all your payments on time, every time. A missed payment won’t usually impact your credit unless you’re 30 days or more past due—but even one slip can lower your score. 2. Is Your Income Reliable? Lenders are trusting you with hundreds of thousands of dollars, so they want to be confident that your income is stable enough to support regular mortgage payments. Salaried employees in permanent positions generally have the easiest time qualifying. If you’re self-employed, or your income includes commission, overtime, or bonuses, expect to provide at least two years’ worth of income documentation. The more predictable your income, the easier it is to qualify. 3. What’s Your Down Payment Plan? Every mortgage requires some amount of money upfront. In Canada, the minimum down payment is: 5% on the first $500,000 of the purchase price 10% on the portion above $500,000 20% for homes over $1 million You’ll also need to show proof of at least 1.5% of the purchase price for closing costs (think legal fees, appraisals, and taxes). The best source of a down payment is your own savings, supported by a 90-day history in your bank account. But gifted funds from immediate family and proceeds from a property sale are also acceptable. 4. How Much Can You Actually Afford? There’s a big difference between what you feel you can afford and what you can prove you can afford. Lenders base your approval on verifiable documentation—not assumptions. Your approval amount depends on a variety of factors, including: Income and employment history Existing debts Credit score Down payment amount Property taxes and heating costs for the home All of these factors are used to calculate your debt service ratios—a key indicator of whether your mortgage is affordable. Start Early, Plan Smart Even if you’re months (or more) away from buying, the best time to start planning is now. When you work with an independent mortgage professional, you get access to expert advice at no cost to you. We can: Review your credit profile Help you understand how lenders view your income Guide your down payment planning Determine how much you can qualify to borrow Build a roadmap if your finances need some fine-tuning If you're ready to start mapping out your home buying plan or want to know where you stand today, let’s talk. It would be a pleasure to help you get mortgage-ready.