Mortgage Approval 101: GDS & TDS Explained

Dean Garrett • October 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.


A man wearing a black shirt is smiling for the camera
Dean Garrett

Mortgage Professional

Best Mortgage Options for Canadian Homebuyers

By Dean Garrett • April 1, 2026
Thinking of Calling Your Bank for a Mortgage? Read This First. If you're buying a home or renewing your mortgage, your first instinct might be to call your bank. It's familiar. It's easy. But it might also cost you more than you realize—in money, flexibility, and long-term satisfaction. Before you sign anything, here are four things your bank won’t tell you—and four reasons why working with an independent mortgage professional is the smarter move. 1. Your Bank Offers Limited Mortgage Options Banks can only offer what they sell. So if your financial situation doesn’t fit neatly into their guidelines—or if you’re looking for competitive terms—you might be out of luck. Working with a mortgage broker? You get access to mortgage products from hundreds of lenders : major banks, credit unions, monoline lenders, alternative lenders, B lenders, and even private funds. That means more options, more flexibility, and a much better chance of finding a mortgage that fits you. 2. Bank Reps Are Salespeople—Not Mortgage Strategists Let’s be honest: most bank mortgage reps are trained to sell their employer’s products—not to analyze your financial goals or tailor a long-term mortgage plan. Their job is to generate revenue for the bank. Independent mortgage professionals are different. We’re not tied to one lender—we’re tied to you. Our job is to shop around, negotiate on your behalf, and recommend the mortgage that offers the best balance of rate, terms, and flexibility. And yes, we get paid by the lender—but only after we find you a mortgage that works for your situation. That creates a win-win-win: you get the best deal, we earn our fee, and the lender earns your business. 3. Banks Don’t Lead with Their Best Rate It’s true. Banks often reserve their best rates for those who ask for them—or threaten to walk. And guess what? Most people don’t. Over 50% of Canadians accept the first renewal offer they get by mail. No questions asked. That’s exactly what the banks count on. Mortgage professionals don’t play that game. We start by finding lenders offering competitive rates upfront, and we handle the negotiations for you. There’s no guesswork, no pressure, and no settling for less than you deserve. 4. Bank Mortgages Are Often More Restrictive Than You Think Not all mortgages are created equal. Some come with hidden traps—especially around penalties. Ever heard of a sky-high prepayment charge when someone breaks their mortgage early? That’s often due to something called an Interest Rate Differential (IRD) —and big banks are notorious for using the harshest IRD calculations. When we help you choose a mortgage, we don’t just focus on the interest rate. We look at the whole picture, including: Prepayment privileges Penalty calculations Portability Future flexibility That way, if your life changes, your mortgage won’t become a financial anchor. A Quick Recap What your bank typically offers: Only their own limited mortgage products Sales-focused representatives, not mortgage strategists Default rates that aren’t usually their best Restrictive contracts with high penalties What an independent mortgage professional delivers: Access to over 200 lenders and customized mortgage solutions Personalized advice and long-term financial strategy Competitive rates and terms upfront Transparent, flexible mortgage options designed around your needs Let’s Talk Before You Sign Your mortgage is likely the biggest financial commitment you’ll ever make. So why settle for a one-size-fits-all solution? If you're buying, refinancing, or renewing, I’d love to help you explore your options, explain the fine print, and find a mortgage that truly works for you. Let’s start with a conversation—no pressure, just good advice.

Breaking Down the Real Costs of Homeownership

By Dean Garrett • March 25, 2026
Don’t Forget About Closing Costs When planning to buy a home, most people focus on saving for the down payment. But the truth is, that’s only part of the equation. To actually finalize the purchase, you’ll also need to budget for closing costs —the out-of-pocket expenses that come up before you get the keys. Closing costs can add up quickly, which is why they should be part of your pre-approval conversation right from the start. Lenders will even require proof that you’ve got enough funds set aside. For example, if you’re getting an insured (high-ratio) mortgage, you’ll need at least 1.5% of the purchase price available in addition to your down payment. That means a 10% down payment actually requires 11.5% of the purchase price in cash to make everything work. Let’s break down some of the most common expenses you should prepare for: 1. Home Inspection & Appraisal Inspection : Paid by you, this gives peace of mind that the property is in good shape and doesn’t have hidden problems. Appraisal : Required by the lender to confirm value. Sometimes this is covered by mortgage insurance, sometimes by you. 2. Legal Fees A lawyer or notary is required to handle the title transfer and make sure the mortgage is properly registered. Legal fees are often one of the larger closing costs—unless you’re also responsible for property transfer tax. 3. Taxes Many provinces charge a property or land transfer tax based on the home’s purchase price. These fees can range from hundreds to thousands of dollars, so you’ll want to factor them in early. 4. Insurance Property insurance is mandatory—lenders won’t release funds without proof that the home is insured on closing day. Optional coverage like mortgage life, disability, or critical illness insurance may also be worth considering depending on your financial plan. 5. Moving Costs Whether you’re renting a truck, hiring movers, or bribing friends with pizza and gas money, moving comes with expenses. Cross-country moves especially can be surprisingly pricey. 6. Utilities & Deposits Setting up new services (electricity, water, internet) can involve connection fees or deposits, particularly if you don’t already have a payment history with the utility provider. Plan Ahead, Stress Less This list covers the big-ticket items, but every purchase is unique. That’s why it pays to have an accurate estimate of your personal closing costs before you make an offer. If you’d like help planning ahead—or want a breakdown tailored to your situation—let’s connect. I’d be happy to walk you through the numbers and make sure you’re fully prepared.