GDS/TDS Ratios Explained

Lindsey Cupelli • November 13, 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.


Lindsey Cupelli

Mortgage Agent

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New to Credit? Let’s Build a Solid Foundation

By Lindsey Cupelli • November 12, 2025
Starting from Scratch: How to Build Credit the Smart Way If you're just beginning your personal finance journey and wondering how to build credit from the ground up, you're not alone. Many people find themselves stuck in the classic credit paradox: you need credit to build a credit history, but you can’t get credit without already having one. So, how do you break in? Let’s walk through the basics—step by step. Credit Building Isn’t Instant—Start Now First, understand this: building good credit is a marathon, not a sprint. For those planning to apply for a mortgage in the future, lenders typically want to see at least two active credit accounts (credit cards, personal loans, or lines of credit), each with a limit of $2,500 or more , and reporting positively for at least two years . If that sounds like a lot—it is. But everyone has to start somewhere, and the best time to begin is now. Step 1: Start with a Secured Credit Card When you're new to credit, traditional lenders often say “no” simply because there’s nothing in your file. That’s where a secured credit card comes in. Here’s how it works: You provide a deposit—say, $1,000—and that becomes your credit limit. Use the card for everyday purchases (groceries, phone bill, streaming services). Pay the balance off in full each month. Your activity is reported to the credit bureaus, and after a few months of on-time payments, you begin to establish a credit score. ✅ Pro tip: Before you apply, ask if the lender reports to both Equifax and TransUnion . If they don’t, your credit-building efforts won’t be reflected where it counts. Step 2: Move Toward an Unsecured Trade Line Once you’ve got a few months of solid payment history, you can apply for an unsecured credit card or a small personal loan. A car loan could also serve as a second trade line. Again, make sure the account reports to both credit bureaus, and always pay on time. At this point, your focus should be consistency and patience. Avoid maxing out your credit, and keep your utilization under 30% of your available limit. What If You Need a Mortgage Before Your Credit Is Ready? If homeownership is on the horizon but your credit history isn’t quite there yet, don’t panic. You still have a few options. One path is to apply with a co-signer —someone with strong credit and income who is willing to share the responsibility. The mortgage will be based on their credit profile, but your name will also be on the loan, helping you build a record of mortgage payments. Ideally, when the term is up and your credit has matured, you can refinance and qualify on your own. Start with a Plan—Stick to It Building credit may take a couple of years, but it all starts with a plan—and the right guidance. Whether you're figuring out your first steps or getting mortgage-ready, we’re here to help. Need advice on credit, mortgage options, or how to get started? Let’s talk.

Everything You Need to Know About Second Mortgages

By Lindsey Cupelli • November 5, 2025
What Is a Second Mortgage, Really? (It’s Not What Most People Think) If you’ve heard the term “second mortgage” and assumed it refers to the next mortgage you take out after your first one ends, you’re not alone. It’s a common misconception—but the reality is a bit different. A second mortgage isn’t about the order of mortgages over time. It’s actually about the number of loans secured against a single property —at the same time. So, What Exactly Is a Second Mortgage? When you first buy a home, your mortgage is registered on the property in first position . This simply means your lender has the primary legal claim to your property if you ever sell it or default. A second mortgage is another loan that’s added on top of your existing mortgage. It’s registered in second position , meaning the lender only gets paid out after the first mortgage is settled. If you sell your home, any proceeds go toward paying off the first mortgage first, then the second one, and any remaining equity is yours. It’s important to note: You still keep your original mortgage and keep making payments on it —the second mortgage is an entirely separate agreement layered on top. Why Would Anyone Take Out a Second Mortgage? There are a few good reasons homeowners choose this route: You want to tap into your home equity without refinancing your existing mortgage. Your current mortgage has great terms (like a low interest rate), and breaking it would trigger hefty penalties. You need access to funds quickly , and a second mortgage is faster and more flexible than refinancing. One common use? Debt consolidation . If you’re juggling high-interest credit card or personal loan debt, a second mortgage can help reduce your overall interest costs and improve monthly cash flow. Is a Second Mortgage Right for You? A second mortgage can be a smart solution in the right situation—but it’s not always the best move. It depends on your current mortgage terms, your equity, and your financial goals. If you’re curious about how a second mortgage could work for your situation—or if you’re considering your options to improve cash flow or access equity—let’s talk. I’d be happy to walk you through it and help you explore the right path forward. Reach out anytime—we’ll figure it out together.