Mortgage Approval 101: GDS & TDS Explained

Tim Lacroix • 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.


Tim Lacroix

Mortgage Broker

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Reposition Your Debts Through Mortgage Financing

By Tim Lacroix • October 1, 2025
If you’re a homeowner looking to optimize your finances, consider taking advantage of your home’s equity to reposition any existing debts you may have. If you’ve accumulated consumer debt, the payments required to service these debts can make it difficult to manage your daily finances. A consolidation mortgage might be a great option for you! Simply put, debt repositioning or debt consolidation is when you combine your consumer debt with a mortgage secured to your home. To make this happen, you’ll borrow against your home’s equity. This can mean refinancing an existing mortgage, securing a home equity line of credit, or taking out a second mortgage. Each mortgage option has its advantages which are best outlined in discussion with an independent mortgage professional. Some of the types of debts that you can consolidate are: Credit Card Unsecured Line of Credit Car Loan Student Loans Personal or Payday Loans Most unsecured debt carries a high interest rate because the lender doesn't have any collateral to fall back on should you default on the loan. However, as a mortgage is secured to your home, the lender has collateral and can provide you with lower rates and more favourable terms. Debt consolidation makes sense because it allows you to take high-interest unsecured debts and reposition them into a single low payment. So, when considering the best mortgage for you, getting a low rate is important, but it’s not everything. Your goal should be to lower your overall cost of borrowing. A mortgage that allows for flexibility in prepayments helps with this. It’s not uncommon to find a mortgage at a great rate that allows you to increase your payments by 15% per payment, double your payments, or make a lump sum payment of up to 15% annually. As additional payments go directly to the principal repayment of the loan, once you’ve consolidated all your debts into a single payment, it’s smart to take advantage of your prepayment privileges by paying more than just your minimum required mortgage payment, as this will help you become debt-free sooner. While there is a lot to unpack here, if you’d like to discuss what using a mortgage to reposition your debts could look like for you, here’s a simple plan we can follow: First, we’ll assess your existing debt to income ratio. We’ll establish your home’s equity. We’ll consider all your mortgage options. Lastly, we’ll reposition your debts to help optimize your finances. If this sounds like the plan for you, the best place to start is to connect directly. It would be a pleasure to work with you.

Smart Strategies to Save for Your Down Payment

By Tim Lacroix • September 24, 2025
How to Start Saving for a Down Payment (Without Overhauling Your Life) Let’s face it—saving money isn’t always easy. Life is expensive, and setting aside extra cash takes discipline and a clear plan. Whether your goal is to buy your first home or make a move to something new, building up a down payment is one of the biggest financial hurdles. The good news? You don’t have to do it alone—and it might be simpler than you think. Step 1: Know Your Numbers Before you can start saving, you need to know where you stand. That means getting clear on two things: how much money you bring in and how much of it is going out. Figure out your monthly income. Use your net (after-tax) income, not your gross. If you’re self-employed or your income fluctuates, take an average over the last few months. Don’t forget to include occasional income like tax returns, bonuses, or government benefits. Track your spending. Go through your last 2–3 months of bank and credit card statements. List out your regular bills (rent, phone, groceries), then your extras (dining out, subscriptions, impulse buys). You might be surprised where your money’s going. This part isn’t always fun—but it’s empowering. You can’t change what you don’t see. Step 2: Create a Plan That Works for You Once you have the full picture, it’s time to make a plan. The basic formula for saving is simple: Spend less than you earn. Save the difference. But in real life, it’s more about small adjustments than major sacrifices. Cut what doesn’t matter. Cancel unused subscriptions or set a dining-out limit. Automate your savings. Set up a separate “down payment” account and auto-transfer money on payday—even if it’s just $50. Find ways to boost your income. Can you pick up a side job, sell unused stuff, or ask for a raise? Consistency matters more than big chunks. Start small and build momentum. Step 3: Think Bigger Than Just Saving A lot of people assume saving for a down payment is the first—and only—step toward buying a home. But there’s more to it. When you apply for a mortgage, lenders look at: Your income Your debt Your credit score Your down payment That means even while you’re saving, you can (and should) be doing things like: Building your credit score Paying down high-interest debt Gathering documents for pre-approval That’s where we come in. Step 4: Get Advice Early Saving up for a home doesn’t have to be a solo mission. In fact, talking to a mortgage professional early in the process can help you avoid missteps and reach your goal faster. We can: Help you calculate how much you actually need to save Offer tips to strengthen your application while you save Explore alternate down payment options (like gifts or programs for first-time buyers) Build a step-by-step plan to get you mortgage-ready Ready to get serious about buying a home? We’d love to help you build a plan that fits your life—and your goals. Reach out anytime for a no-pressure conversation.