GDS/TDS Ratios Explained

Jeff Johnson • November 6, 2024

One of the major qualifiers lenders look at when considering your application for mortgage financing is your debt service ratios.


Now, before we get started, if you prefer to have someone walk through these calculations with you, assess your financial situation, and let you know exactly where you stand, let’s connect. There is no use in dusting off the calculator and running the numbers yourself when we can do it for you!


However, if you’re someone who likes to know the nitty-gritty of how things work instead of simply accepting that's just the way it is, this article is for you. But be warned, there are a lot of mortgage words and some math ahead; with that out of the way, let’s get started!

 

“Debt servicing” is the measure of your ability to meet all of your financial obligations. There are two ratios that lenders examine to determine whether you can debt service a mortgage.


The first is called the “gross debt service” ratio, or GDS, which is the percentage of your monthly household income that covers your housing costs. The second is called the “total debt service” ratio, or TDS, which is the percentage of your monthly household income covering your housing costs and all your other debts.


GDS is your income compared to the cost of financing the mortgage, including your proposed mortgage payments (principal and interest), property taxes, and heat (PITH), plus a percentage of your condo fees (if applicable).


Here’s how to calculate your GDS.


Principal + Interest + Taxes + Heat / Gross Annual Income


Your TDS is your income compared to your GDS plus the payments made to service any existing debts. Debts include car loans, line of credit, credit card payments, support payments, student loans, and anywhere else you’re contractually obligated to make payments.


Here’s how to calculate your TDS.


Principal + Interest + Taxes + Heat + Other Debts / Gross Annual Income


With the calculations for those ratios in place, the next step is to understand that each lender has guidelines that outline a maximum GDS/TDS. Exceeding these guidelines will result in your mortgage application being declined, so the lower your GDS/TDS, the better.


If you don’t have any outstanding debts, your GDS and TDS will be the same number. This is a good thing!


The maximum ratios vary for conventional mortgage financing based on the lender and mortgage product being offered. However, if your mortgage is high ratio and mortgage default insurance is required, the maximum GDS is 39% with a maximum TDS of 44%.


So how does this play out in real life? Well, let’s say you’re currently looking to purchase a property with a payment of $1700/mth (PITH), and your total annual household income is $90,000 ($7500/mth). The calculations would be $1700 divided by $7500, which equals 0.227, giving you a gross debt service ratio of 22.7%.


A point of clarity here. When calculating the principal and interest portion of the payment, the Government of Canada has instituted a stress test. It requires you to qualify using the government's qualifying rate (which is higher), not the actual contract rate. This is true for both fixed and variable rate mortgages.


Now let’s continue with the scenario. Let’s say that in addition to the payments required to service the property, you have a car payment of $300/mth, child support payments of $500/mth, and between your credit cards and line of credit, you’re responsible for another $700/mth. In total, you pay $1500/mth. So when you add in the $1700/mth PITH, you arrive at a total of $3200/mth for all of your financial obligations. $3200 divided by $7500 equals 0.427, giving you a total debt service ratio of 42.7%.


Here’s where it gets interesting. Based on your GDS alone, you can easily afford the property. But when you factor in all your other expenses, the TDS exceeds the allowable limit of 42% (for an insured mortgage anyway). So why does this matter? Well, as it stands, you wouldn’t qualify for the mortgage, even though you are likely paying more than $1700/mth in rent.


So then, to qualify, it might be as simple as shuffling some of your debt to lower payments. Or maybe you have 10% of the purchase price saved for a downpayment, changing the mortgage structure to 5% down and using the additional 5% to pay out a portion of your debt might be the difference you need to bring it all together.


Here’s the thing, as your actual financial situation is most likely different than the one above, working with an independent mortgage professional is the best way to give yourself options. Don’t do this alone. Your best plan is to seek and rely on the advice provided by an experienced independent mortgage professional. While you might secure a handful of mortgages over your lifetime, we do this every day with people just like you.


It’s never too early to start the conversation about mortgage qualification. Going over your application and assessing your debt service ratios in detail beforehand gives you the time needed to make the financial moves necessary to put yourself in the best financial position.


So if you find yourself questioning what you can afford or if you want to discuss your GDS/TDS ratios to understand the mortgage process a little better, please get in touch. It would be a pleasure to work with you, we can get a preapproval started right away.

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.