GDS/TDS Ratios Explained

Tim Lyon • November 16, 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.

Tim Lyon

Mortgage Consultant

Mortgage Renewal vs. Refinance: Understanding the Key Differences

By Tim Lyon • November 25, 2025
If you own a property with a mortgage, you've probably heard the terms "renewal" and "refinance" thrown around. While both involve obtaining a new term for your mortgage, there are some important differences to understand. Let's break down what each one means and when you might use them. Understanding Mortgage Basics In Canada, when you take out a mortgage, the payments are typically spread over 25 to 30 years. This period is known as the amortization. However, unlike in the U.S., Canadians do not keep the same interest rate and payment terms for the entire amortization period. Instead, you have an initial term, usually 3 to 5 years, after which you need to renew into a new term. For example, if you have a 25-year mortgage with 5-year terms, you will need to renew your mortgage four times throughout its lifespan. It's also common to have a mix of different term lengths over the course of your mortgage. What is a Mortgage Renewal? A mortgage renewal occurs at the end of your mortgage term. When you renew, you start a new term with a new interest rate while keeping the remaining details of your mortgage the same. The key element here is that the mortgage charge registered on your property's title remains unchanged. A renewal is straightforward and typically does not involve any significant changes to your mortgage agreement other than a new interest rate. Think of it as hitting the "continue" button on your mortgage, but at new rates. What is a Mortgage Refinance? A mortgage refinance is different. When you refinance, you are making changes to your original mortgage agreement. This means paying off your existing mortgage and registering a new one on your property's title. Essentially, you are taking out a completely new mortgage for the same property. People commonly refinance to: Access the equity in their home for investments or major purchases Consolidate high-interest debt into their lower-rate mortgage Extend the amortization period to reduce monthly payments and improve cash flow Make significant changes to their mortgage structure It's important to note that refinancing is not allowed for insured properties (those with less than a 20% down payment at purchase). This means the maximum loan amount in a refinance is 80% of your property value. What About Switching Lenders? If you want to keep everything the same but switch lenders for a better rate, this is known as a transfer. A transfer is a type of renewal where the original mortgage charge is transferred from one lender to another. Depending on the lenders involved, you might be able to make minor changes (like extending the amortization or changing borrowers) without needing a full refinance. Why Timing Matters Your mortgage maturity date is when your current term ends. This is the ideal time to either renew or refinance. If you refinance or switch lenders before the maturity date, you will face a prepayment penalty. If you refinance, renew or transfer at maturity, there is no penalty. Real-World Example A homeowner with a $450,000 mortgage is reaching the end of their 5-year term. Their lender offers a renewal rate, but they also have $40,000 in high-interest credit card debt. Option 1: Renewal They accept the new term. Their mortgage stays the same. Their debt remains separate at high interest rates. Option 2: Refinance at Maturity They consolidate the credit card debt into the new mortgage. Their total monthly payments drop significantly, even after accounting for the new mortgage balance. In this situation, refinancing provides better cash flow and a simpler payment structure. Quick Summary Mortgage Renewal: Starts a new term for your existing mortgage Mortgage charge on your title stays the same Keeps all other terms the same aside from interest rate Can switch lenders at renewal through a transfer No penalty when done at maturity Mortgage Refinance: Pays off current mortgage and creates a new one New mortgage charge registered on your title Often resets the amortization period Can access equity or make structural changes Maximum 80% of property value for uninsured mortgages Incurs penalty if done before maturity Next Steps Understanding the difference between renewal and refinance helps you make informed decisions about managing your mortgage. If you have a renewal coming up or are considering accessing your home equity, now is a good time to explore your options. Whether you're looking to renew, refinance, or switch lenders, I'm here to help you navigate the process and find the best solution for your situation. Need help with your mortgage? Book a consultation or call 778-988-8409 . Glossary Amortization: The total time period over which you'll pay off your mortgage, typically 25-30 years in Canada. Insured Mortgage: A mortgage where the down payment was less than 20%, requiring mortgage default insurance to be added. Maturity Date: The end date of your current mortgage term, when you need to renew or refinance. Mortgage Charge: The legal registration of your mortgage on your property's title. Pre-payment Penalty: A fee charged by your lender if you pay off your mortgage before the end of your term. Refinance: Replacing your existing mortgage with a new mortgage, often with different terms or to access equity. Renewal: Starting a new term for your existing mortgage, typically just updating the interest rate. Term: The length of time your current mortgage contract is in effect, typically 3-5 years in Canada. Transfer: Moving your mortgage from one lender to another at renewal without changing other terms.

What Is an Insured Mortgage and How Does It Work?

By Tim Lyon • October 28, 2025
If you're buying a home with less than 20% down, you'll need something called an insured mortgage. Many borrowers find this confusing at first, especially since it doesn’t refer to insurance for you, the borrower. That’s why I have put together this straightforward breakdown so you understand what insured mortgages are, why they exist, and how they affect your purchase. What Is an Insured Mortgage? A mortgage must be insured when a borrower makes a down payment of less than 20% on a home purchase. The insurance protects the lender (not the borrower) in case the borrower defaults. The insurance is guaranteed by the federal government. So, why do we have this program? It allows borrowers to buy homes with smaller down payments and higher loan-to-value (LTV) ratios. Higher loan-to-value mortgages are inherently more risky because there is not much cushion if the housing market starts to decline. For example, if someone buys a $500,000 home with only 5% down ($25,000), they’ll need a $475,000 mortgage—this is a 95% LTV . If the market drops and the home’s value falls to $470,000, the mortgage would still be $475,000. If the borrower stopped making payments, the lender could lose money after selling the home and paying costs. That kind of loss, multiplied across thousands of borrowers, could threaten the stability of the entire banking system (as we saw in the U.S. in 2008). The mortgage insurance system is designed to prevent that scenario by spreading risk and keeping lenders protected. How Does the Insurance Work? You, the borrower, pay the insurance premium. It's typically added directly to your mortgage balance rather than paid upfront. The cost depends on your down payment size and amortization. Example: Purchase price: $500,000 Down payment: $25,000 (5%) Mortgage amount: $475,000 Insurance premium: 4.2% = $19,950 Total new mortgage: $494,950 The insurance does add cost, but insured mortgages usually offer slightly lower interest rates because the lender's risk is minimal. The rate savings don't fully offset the premium, but they help. The Insurer’s Role For insured mortgages, the insurer’s approval is the most important part of the process. If the insurer won’t approve the file, no lender can. Once the insurer signs off, we can typically find a lender to fund the loan. Canada has three mortgage insurers: CMHC (public) Sagen (private) Canada Guaranty (private) All of the insurers are backed by government guarantees and have to follow similar rules, but each has a few unique programs. Lenders usually choose the insurer, though I sometimes work with them to send a file to a specific insurer if it benefits the borrower. Qualification Rules Because insured mortgages are government-backed, the rules are strict: Debt ratios: 39% of your income can go toward your stress-tested mortgage payment, property taxes, heat, and half of condo fees 44% of your income can go toward the above plus your other debts Down payment: 5% on the first $500,000, 10% on the remainder Maximum purchase price: $1.5 million Amortization: Maximum of 25 years for most buyers; up to 30 years for first-time buyers who qualify under the new federal program Unlike with an uninsured mortgage, where lenders may have some flexibility if your income ratios are slightly above the limits, there is no discretion on an insured mortgage. If your ratios exceed the limits even a little bit, the insurer will decline the application. The Approval Process The process is similar to an uninsured mortgage, with one extra step: We submit your mortgage application to the lender of choice They do their initial review If that looks good, they package it up and send it to the insurer Once the insurer has reviewed and approved it, the file comes back to the lender for final review and approval Common Misunderstandings About Insured Mortgages Many borrowers are surprised to learn the following facts about insured mortgages: You do not need to be a first-time homebuyer to buy with less than 20% down You cannot buy an investment property with less than 20% down You can buy a second home with less than 20% down You cannot refinance an insured mortgage and keep the insurance. If you have an insured mortgage and do refinance, you will lose the insurance. This mostly affects the lender, but it also moves you to uninsured rates. Why Choose an Insured Mortgage? Given the cost and restrictions, why would anyone choose an insured mortgage? The main reason is accessibility . It allows you to buy a home without saving a full 20% down payment, which is increasingly difficult with high home prices and living costs. It can also be a strategic choice. Some buyers prefer to keep more of their savings invested or diversified instead of tying everything up in a down payment. If your investments are earning more than your mortgage costs, keeping that money invested might make financial sense. Real-World Example Let's say you're buying a $600,000 home. Here's how the costs compare between the minimum down payment for an insured mortgage and the minimum down payment for an uninsured mortgage: