Mortgage Approval 101: GDS & TDS Explained

Jeff Johnson • September 10, 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.


Jeff Johnson

Mortgage Expert

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How to Finance Renovations When Buying a Home in Canada

By Jeff Johnson • August 19, 2026
Can’t Find the Right Home After You’re Pre-Approved? There’s Another Option The best place to start any home purchase is with a mortgage pre-approval. It gives you clarity around your budget and lets you shop with confidence. But what happens when you’ve been pre-approved, you know where you want to live—and nothing suitable fits your price range? This is a common challenge, especially for first-time homebuyers. Before buyer fatigue sets in, it may be worth considering a different approach: buying a home that needs work and financing the renovations as part of your mortgage . What Is a Purchase Plus Improvements Mortgage? A purchase plus improvements program allows you to buy a property and include the cost of approved renovations directly in your mortgage. This can be a great solution if: You can’t find a move-in-ready home within budget You’re open to renovations You want to customize the home from the start It opens up more options and can help you get into a location or property that would otherwise be out of reach. How the Process Works While the idea is straightforward, the process itself is structured and requires planning. Here’s a high-level overview: Renovation quotes are required upfront You’ll need detailed quotes for the work you want completed before final mortgage approval. Renovations must add value The lender must be satisfied that the improvements will increase the property’s value accordingly. Funds are reimbursed, not advanced You pay for the renovations initially. Once the work is completed and verified by an appraiser, the lender reimburses you and adds the cost to your mortgage. With the right guidance, this process is very manageable—but it’s important to understand the steps before committing. Is This Program Right for You? Purchase plus improvements isn’t for everyone. Buying a home is already a big undertaking, and adding renovations can increase stress—especially if timelines, budgets, or contractors become challenging. That said, if you’re financially prepared and like the idea of shaping the home to fit your needs, this program can be an excellent way to get more value and flexibility from your purchase. Final Thoughts If you’re struggling to find the right home after being pre-approved, you may not need to lower your expectations—you may just need a different strategy. If you’d like to explore whether a purchase plus improvements mortgage makes sense for you, feel free to connect. I’d be happy to walk you through the process and outline exactly what this option would look like in your situation.

Fell Behind on a Payment? Don’t Panic—Here’s What to Do

By Jeff Johnson • August 12, 2026
Missed a Credit Card or Line of Credit Payment? Here’s What to Do If you’ve missed a payment on a credit card or line of credit and you’re worried about how it might affect your credit—or your future mortgage—this is for you. First things first: 👉 If you currently have an overdue balance, log in and make the minimum payment now. Seriously. Do that first. Everything else can wait. If You’re Only a Few Days Late Here’s the good news: Credit bureaus don’t record late payments until they reach 30 days past due. So if you missed a due date by a few days and paid it as soon as you noticed, it typically won’t show up on your credit report as a late payment—as long as you’re under the 30-day mark. That said, it never hurts to double-check. You can call your credit card company, explain what happened, and confirm the account is back in good standing. If you normally pay on time, they may even reverse the interest charged. It doesn’t hurt to ask. If You’re 30, 60, or 90 Days Behind If payments have gone past 30 days, your credit has likely been impacted—but the situation is still fixable. The most important step is to: Bring all accounts current as soon as possible Make at least the minimum payment on every account The faster you catch up, the more you limit the damage. Ignoring missed payments only makes things worse. If Cash Flow Is Tight If you’re struggling to make payments, communication matters. Contact your lender and keep them informed—even if you can’t pay right away. Lenders are far more willing to work with you when you’re transparent. What hurts your credit most is silence . If lenders don’t hear from you after repeated missed payments, they may write the balance off as bad debt and send it to collections. Collections can significantly impact your credit and stay on your report for years. How This Affects Mortgage Qualification Repeated missed payments can make qualifying for a mortgage more difficult—but timing matters. Once you’re back to making regular, on-time payments: Your credit can improve over time The impact of past mistakes becomes less significant If you’re planning to buy a home in the next couple of years, addressing credit issues early gives you far more options later. Final Thoughts Missing a payment doesn’t mean you’re “bad with money,” and it doesn’t mean homeownership is off the table. What matters most is how quickly you respond and how consistent you are going forward . If you’d like help reviewing your credit report or understanding where you stand from a mortgage perspective, feel free to connect. I’d be happy to walk through it with you and help you create a clear path forward.