What Are GDS/TDS Ratios Anyways?

Rita Wagner • July 6, 2023

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.


Share

RITA WAGNER
MORTGAGE PROFESSIONAL

403-502-3330

rita@ritawagner.ca

RECENT POSTS 

By Rita Wagner April 30, 2026
Your Guide to Real Estate Investment in Canada Real estate has long been one of the most popular ways Canadians build wealth. Whether you’re purchasing your first rental property or expanding an existing portfolio, understanding how real estate investment works in Canada—and how it’s financed—is key to making smart decisions. This guide walks through the fundamentals you need to know before getting started. Why Canadians Invest in Real Estate Real estate offers several potential benefits as an investment: Long-term appreciation of property value Rental income that can support cash flow Leverage , allowing you to invest using borrowed funds Tangible asset with intrinsic value Portfolio diversification beyond stocks and bonds When structured properly, real estate can support both income and long-term net worth growth. Types of Real Estate Investments Investors typically focus on one or more of the following: Long-term residential rentals Short-term or vacation rentals (subject to local regulations) Multi-unit residential properties Pre-construction or assignment purchases Value-add properties that require renovations Each type comes with different financing rules, risks, and return profiles. Down Payment Requirements for Investment Properties In Canada, investment properties generally require higher down payments than owner-occupied homes. Typical minimums include: 20% down payment for most rental properties Higher down payments may be required depending on: Number of units Property type Borrower profile Lender guidelines Down payment source, income stability, and credit history all play a role in approval. How Rental Income Is Used to Qualify Lenders don’t always count 100% of rental income. Depending on the lender and mortgage product, they may: Use a rental income offset , or Include a percentage of rental income toward qualification Understanding how income is treated can significantly impact borrowing power. Financing Options for Investors Investment financing can include: Conventional mortgages Insured or insurable options (in limited scenarios) Alternative or broker-only lenders Refinancing equity from existing properties Purchase plus improvements for value-add projects Access to multiple lenders is often crucial for investors as portfolios grow. Key Costs Investors Should Plan For Beyond the purchase price, investors should budget for: Property taxes Insurance Maintenance and repairs Vacancy periods Property management fees (if applicable) Legal and closing costs A realistic cash-flow analysis is essential before buying. Risk Considerations Like any investment, real estate carries risk. Key factors to consider include: Interest rate changes Market fluctuations Tenant turnover Regulatory changes Liquidity (real estate is not easily sold quickly) A strong financing structure can help manage many of these risks. The Role of a Mortgage Professional Investment mortgages are rarely “one-size-fits-all.” Lender policies vary widely, especially as you acquire more properties. Working with an independent mortgage professional allows you to: Compare multiple lender strategies Structure financing for long-term growth Preserve flexibility as your portfolio evolves Avoid costly mistakes early on Final Thoughts Real estate investment in Canada can be a powerful wealth-building tool when approached with a clear strategy and proper financing. Whether you’re exploring your first rental property or planning your next acquisition, understanding the numbers—and the lending landscape—matters. If you’d like to discuss investment property financing, run the numbers, or explore your options, feel free to connect. A well-planned mortgage strategy can make all the difference in long-term success.
By Rita Wagner April 29, 2026
The Bank of Canada announced today that it is holding its target for the overnight rate at 2.25%, with the Bank Rate at 2.5% and the deposit rate at 2.20%. This decision comes against a backdrop of significant global uncertainty — and for Canadian homeowners, buyers, and anyone with a mortgage coming up for renewal, here's what it means.
By Rita Wagner April 16, 2026
Thinking About Selling Your Home? Start With These 3 Key Questions Selling your home is a major move—emotionally, financially, and logistically. Whether you're upsizing, downsizing, relocating, or just ready for a change, there are a few essential questions you should have answers to before you list that "For Sale" sign. 1. How Will I Get My Home Sale-Ready? Before your property hits the market, you’ll want to make sure it puts its best foot forward. That starts with understanding its current market value—and ends with a plan to maximize its appeal. A real estate professional can walk you through what similar homes in your area have sold for and help tailor a prep plan that aligns with current market conditions. Here are some things you might want to consider: Decluttering and removing personal items Minor touch-ups or repairs Fresh paint inside (and maybe outside too) Updated lighting or fixtures Professional staging Landscaping or exterior cleanup High-quality photos and possibly a virtual tour These aren’t must-dos, but smart investments here can often translate to a higher sale price and faster sale. 2. What Will It Actually Cost to Sell? It’s easy to look at the selling price and subtract your mortgage balance—but the real math is more nuanced. Here's a breakdown of the typical costs involved in selling a home: Real estate agent commissions (plus GST/HST) Legal fees Mortgage discharge fees (and possibly a penalty) Utility and property tax adjustments Moving expenses and/or storage costs That mortgage penalty can be especially tricky—it can sometimes be thousands of dollars, depending on your lender and how much time is left in your term. Not sure what it might cost you? I can help you estimate it. 3. What’s My Plan After the Sale? Knowing your next step is just as important as selling your current home. If you're buying again, don’t assume you’ll automatically qualify for a new mortgage just because you’ve had one before. Lending rules change, and so might your financial situation. Before you sell, talk to a mortgage professional to find out what you’re pre-approved for and what options are available. If you're planning to rent or relocate temporarily, think about timelines, storage, and transition costs. Clarity and preparation go a long way. The best way to reduce stress and make confident decisions is to work with professionals you trust—and ask all the questions you need. If you’re thinking about selling and want help mapping out your next steps, I’d be happy to chat anytime. Let’s make a smart plan, together.
Show More