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

APPLY NOW

Fixed-Rate or Variable-Rate Mortgage?

By Tim Lacroix • August 13, 2025
If you're looking to buy a new property, refinance, or renew an existing mortgage, chances are, you're considering either a fixed or variable rate mortgage. Figuring out which one is the best is entirely up to you! So here's some information to help you along the way. Firstly, let's talk about the fixed-rate mortgage as this is most common and most heavily endorsed by the banks. With a fixed-rate mortgage, your interest rate is "fixed" for a certain term, anywhere from 6 months to 10 years, with the typical term being five years. If market rates fluctuate anytime after you sign on the dotted line, your mortgage rate won't change. You're a rock; your rate is set in stone. Typically a fixed-rate mortgage has a higher rate than a variable. Alternatively, a variable rate is not set in stone; instead, it fluctuates with the market. The variable rate is a component (either plus or minus) to the prime rate. So if the prime rate (set by the government and banks) is 2.45% and the current variable rate is Prime minus .45%, your effective rate would be 2%. If three months after you sign your mortgage documents, the prime rate goes up by .25%, your rate would then move to 2.25%. Typically, variable rates come with a five-year term, although some lenders allow you to go with a shorter term. At first glance, the fixed-rate mortgage seems to be the safe bet, while the variable-rate mortgage appears to be the wild card. However, this might not be the case. Here's the problem, what this doesn't account for is the fact that a fixed-rate mortgage and a variable-rate mortgage have two very different ways of calculating the penalty should you need to break your mortgage. If you decide to break your variable rate mortgage, regardless of how much you have left on your term, you will end up owing three months interest, which works out to roughly two to two and a half payments. Easy to calculate and not that bad. With a fixed-rate mortgage, you will pay the greater of either three months interest or what is called an interest rate differential (IRD) penalty. As every lender calculates their IRD penalty differently, and that calculation is based on market fluctuations, the contract rate at the time you signed your mortgage, the discount they provided you at that time, and the remaining time left on your term, there is no way to guess what that penalty will be. However, with that said, if you end up paying an IRD, it won't be pleasant. If you've ever heard horror stories of banks charging outrageous penalties to break a mortgage, this is an interest rate differential. It's not uncommon to see penalties of 10x the amount for a fixed-rate mortgage compared to a variable-rate mortgage or up to 4.5% of the outstanding mortgage balance. So here's a simple comparison. A fixed-rate mortgage has a higher initial payment than a variable-rate mortgage but remains stable throughout your term. The penalty for breaking a fixed-rate mortgage is unpredictable and can be upwards of 4.5% of the outstanding mortgage balance. A variable-rate mortgage has a lower initial payment than a fixed-rate mortgage but fluctuates with prime throughout your term. The penalty for breaking a variable-rate mortgage is predictable at 3 months interest which equals roughly two and a half payments. The goal of any mortgage should be to pay the least amount of money back to the lender. This is called lowering your overall cost of borrowing. While a fixed-rate mortgage provides you with a more stable payment, the variable rate does a better job of accommodating when "life happens." If you’ve got questions, connect anytime. It would be a pleasure to work through the options together.

Start Smart: Get Pre-Approved for Your Mortgage

By Tim Lacroix • August 6, 2025
Thinking of Buying a Home? Here’s Why Getting Pre-Approved Is Key If you’re ready to buy a home but aren’t sure where to begin, the answer is simple: start with a pre-approval. It’s one of the most important first steps in your home-buying journey—and here's why. Why a Pre-Approval is Crucial Imagine walking into a restaurant, hungry and excited to order, but unsure if your credit card will cover the bill. It’s the same situation with buying a home. You can browse listings online all day, but until you know how much you can afford, you’re just window shopping. Getting pre-approved for a mortgage is like finding out the price range you can comfortably shop within before you start looking at homes with a real estate agent. It sets you up for success and saves you from wasting time on properties that might be out of reach. What Exactly is a Pre-Approval? A pre-approval isn’t a guarantee. It’s not a promise that a lender will give you a mortgage no matter what happens with your finances. It’s more like a preview of your financial health, giving you a clear idea of how much you can borrow, based on the information you provide at the time. Think of it as a roadmap. After going through the pre-approval process, you’ll have a much clearer picture of what you can afford and what you need to do to make the final approval process smoother. What Happens During the Pre-Approval Process? When you apply for a pre-approval, lenders will look at a few key areas: Your income Your credit history Your assets and liabilities The property you’re interested in This comprehensive review will uncover any potential hurdles that could prevent you from securing financing later on. The earlier you identify these challenges, the better. Potential Issues a Pre-Approval Can Reveal Even if you feel confident that your finances are in good shape, a pre-approval might uncover issues you didn’t expect: Recent job changes or probation periods An income that’s heavily commission-based or reliant on extra shifts Errors or collections on your credit report Lack of a well-established credit history Insufficient funds saved for a down payment Existing debt reducing your qualification amount Any other financial blind spots you might not be aware of By addressing these issues early, you give yourself the best chance of securing the mortgage you need. A pre-approval makes sure there are no surprises along the way. Pre-Approval vs. Pre-Qualification: What’s the Difference? It’s important to understand that a pre-approval is more than just a quick online estimate. Unlike pre-qualification—which can sometimes be based on limited information and calculations—a pre-approval involves a thorough review of your finances. This includes looking at your credit report, providing detailed documents, and having a conversation with a mortgage professional about your options. Why Get Pre-Approved Now? The best time to secure a pre-approval is as soon as possible. The process is free and carries no risk—it just gives you a clear path forward. It’s never too early to start, and by doing so, you’ll be in a much stronger position when you're ready to make an offer on your dream home. Let’s Make Your Home Buying Journey Smooth A well-planned mortgage process can make all the difference in securing your home. If you’re ready to get pre-approved or just want to chat about your options, I’d love to help. Let’s make your home-buying experience a smooth and successful one!