Mortgage Approval 101: GDS & TDS Explained

Josh Perez • August 13, 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.


Josh Perez
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Get Unbiased Advice: Work with an Independent Mortgage Pro

By Josh Perez • December 24, 2025
Why Work With an Independent Mortgage Professional? If you’re in the market for a mortgage, here’s the most important thing to know: Working with an independent mortgage professional can save you money and provide better options than dealing directly with a single bank. If that’s all you read—great! But if you’d like to understand why that statement is true, keep reading. The Best Mortgage Isn’t Just About the Lowest Rate It’s easy to fall for slick marketing that promotes ultra-low mortgage rates. But the lowest rate doesn’t always mean the lowest cost . The best mortgage is the one that costs you the least amount of money over time —not just the one with the flashiest headline rate. Things like: Prepayment penalties Portability Flexibility to refinance Amortization structure Fixed vs. variable terms …can all affect the true cost of your mortgage. An independent mortgage professional looks beyond the rate. They’ll help you find a product that fits your unique financial situation , long-term goals, and lifestyle—so you’re not hit with expensive surprises down the road. Save Time (and Your Sanity) Applying for a mortgage can be complicated. Every lender has different rules, documents, and policies—and trying to navigate them all on your own can be time-consuming and frustrating. When you work with an independent mortgage professional: You fill out one application They shop that application across multiple lenders You get expert advice tailored to your needs This means less paperwork , less stress , and more confidence in your options. Get Unbiased Advice That Puts You First Bank specialists work for the bank. Their job is to sell you that bank’s mortgage products—whether or not it’s the best deal for you. Independent mortgage professionals work for you. They’re provincially licensed, and their job is to help you: Compare multiple lenders Understand the fine print Make informed, long-term financial decisions And the best part? Their services are typically free to you . Mortgage professionals are paid a standardized fee by the lender when a mortgage is placed—so you get expert guidance without any out-of-pocket cost. Access More Mortgage Options When you go to your bank, you’re limited to that bank’s mortgage products. When you go to an independent mortgage professional, you get access to: Major banks Credit unions Monoline lenders (who only offer mortgages) Alternative and private lenders (if needed) That’s far more choice , and a much better chance of finding a mortgage that truly fits your needs and goals. The Bottom Line If you want to: Save money over the life of your mortgage Save time by avoiding unnecessary back-and-forth Access more lenders and products Get honest, client-first advice …then working with an independent mortgage professional is one of the smartest decisions you can make. Let’s Make a Plan That Works for You If you're ready to talk about mortgage financing—or just want to explore your options—I'm here to help. Let's connect and put together a strategy that makes sense for your goals and your future. Reach out anytime. I’d be happy to help.

Why High Income Doesn’t Automatically Mean a Bigger Mortgage

By Josh Perez • December 18, 2025
Most people assume a bigger paycheck leads to a bigger mortgage approval. But here’s the truth that surprises almost everyone: “It’s not about how much you earn. It’s about how much of your income is already spoken for.” — Josh Perez I’ve sat across from clients earning six figures who qualified for less than someone making half as much. The problem wasn’t their income. It was their monthly obligations . Lenders Don’t Just Look at Income — They Look at What’s Left Over You can make $200,000 a year, but if $80,000 of it is tied up in payments, lenders see very little room for a mortgage. Here’s what typically eats up that space: Big car loans Multiple credit cards Buy-now-pay-later plans Personal loans Lines of credit Old debts that still report monthly payments These commitments matter because lenders are focused on one main calculation: Debt-to-Income Ratio (DTI) This tells lenders how much of your income is already locked into payments — and how much is available for a mortgage. A high DTI = lower mortgage approval A low DTI = stronger approval and better options It’s that simple. Want to Qualify for More? Do This First Most people think they need to increase their income. The truth? Reducing debt often has a bigger impact — and works faster. 1. Pay down or eliminate high monthly payments Even paying off a single loan can shift your approval dramatically. 2. Avoid taking on new credit before applying Every new payment reduces your borrowing room. 3. Keep your spending stable for 90 days Lenders review recent bank history. Stability helps. 4. Work with a mortgage broker, not just one bank This is one of the biggest ways people leave money on the table. Every lender calculates affordability differently. Some are far more flexible with DTI. If you only go to your bank, you’re only getting one version of your potential approval. Let’s Make Your Approval Work for You If you want to qualify for more, reduce debt strategically, or understand where you stand right now, I can help you build the right plan. Let’s give you access to more options — not just one.