Mortgage Approval 101: GDS & TDS Explained

Sarah Hainsworth • September 3, 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.


Sarah Hainsworth
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Divorce and Your Mortgage: What You Need to Know

By Sarah Hainsworth • November 12, 2025
Going Through a Separation? Here’s What You Need to Know About Your Mortgage Separation or divorce can be one of life’s most stressful transitions—and when real estate is involved, the financial side of things can get complicated fast. If you and your partner own a home together, figuring out what happens next with your mortgage is a critical step in moving forward. Here’s what you need to know: You’re Still Responsible for Mortgage Payments Even if your relationship changes, your obligation to your mortgage lender doesn’t. If your name is on the mortgage, you’re fully responsible for making sure payments continue. Missed payments can lead to penalties, damage your credit, or even put your home at risk of foreclosure. If you relied on your partner to handle payments during the relationship, now is the time to take a proactive role. Contact your lender directly to confirm everything is on track. Breaking or Changing Your Mortgage Comes With Costs Dividing your finances might mean refinancing, removing someone from the title, or selling the home. All of these options come with potential legal fees, appraisal costs, and mortgage penalties—especially if you’re mid-term with a fixed-rate mortgage. Before making any decisions, speak with your lender to get a clear picture of the potential costs. This info can be helpful when finalizing your separation agreement. Legal Status Affects Financing If you're applying for a new mortgage after a separation, lenders will want to see official documentation—like a signed separation agreement or divorce decree. These documents help the lender assess any ongoing financial obligations like child or spousal support, which may impact your ability to qualify. No paperwork yet? Expect delays and added scrutiny in the mortgage process until everything is finalized. Qualifying on One Income Can Be Tougher Many couples qualify for mortgages based on combined income. After a separation, your borrowing power may decrease if you're now applying solo. This can affect your ability to buy a new home or stay in the one you currently own. A mortgage professional can help you reassess your financial picture and identify options that make sense for your situation—whether that means buying on your own, co-signing with a family member, or exploring government programs. Buying Out Your Partner? You May Have Extra Flexibility In cases where one person wants to stay in the home, lenders may offer special flexibility. Unlike traditional refinancing, which typically caps borrowing at 80% of the home’s value, a “spousal buyout” may allow you to access up to 95%—making it easier to compensate your former partner and retain the home. This option is especially useful for families looking to minimize disruption for children or maintain community ties. You Don’t Have to Figure It Out Alone Separation is never simple—but with the right support, you can move forward with clarity and confidence. Whether you’re keeping the home, selling, or starting fresh, working with a mortgage professional can help you understand your options and create a strategy that aligns with your new goals. Let’s talk through your situation and explore the best path forward. I’m here to help.

Your Guide to Successfully Navigating the Housing Market

By Sarah Hainsworth • November 5, 2025
Wondering If Now’s the Right Time to Buy a Home? Start With These Questions Instead. Whether you're looking to buy your first home, move into something bigger, downsize, or find that perfect place to retire, it’s normal to feel unsure—especially with all the noise in the news about the economy and the housing market. The truth is, even in the most stable times, predicting the “perfect” time to buy a home is incredibly hard. The market will always have its ups and downs, and the headlines will never give you the full story. So instead of trying to time the market, here’s a different approach: Focus on your personal readiness—because that’s what truly matters. Here are some key questions to reflect on that can help bring clarity: Would owning a home right now put me in a stronger financial position in the long run? Can I comfortably afford a mortgage while maintaining the lifestyle I want? Is my job or income stable enough to support a new home? Do I have enough saved for a down payment, closing costs, and a little buffer? How long do I plan to stay in the property? If I had to sell earlier than planned, would I be financially okay? Will buying a home now support my long-term goals? Am I ready because I want to buy, or because I feel pressure to act quickly? Am I hesitating because of market fears, or do I have legitimate concerns? These are personal questions, not market ones—and that’s the point. The economy might change tomorrow, but your answers today can guide you toward a decision that actually fits your life. Here’s How I Can Help Buying a home doesn’t have to be stressful when you have a plan and someone to guide you through it. If you want to explore your options, talk through your goals, or just get a better sense of what’s possible, I’m here to help. The best place to start? A mortgage pre-approval . It’s free, it doesn’t lock you into anything, and it gives you a clear picture of what you can afford—so you can move forward with confidence, whether that means buying now or waiting. You don’t have to figure this out alone. If you’re curious, let’s talk. Together, we can map out a homebuying plan that works for you.