The Number Your Lender Gives You Is Not the Number You Should Spend
A friend of mine got pre-approved for $485,000 last March. She earns $112,000 a year, has modest student loan payments, and a credit score north of 760. On paper, the math checked out. The lender ran her through the standard debt-to-income calculation, stamped the approval, and wished her luck.
She bought a house for $470,000. Within eight months, she was skipping contributions to her 401(k), had stopped putting money into her Roth IRA, and was dipping into her emergency fund every time a quarterly insurance payment came due. She wasn’t living lavishly — she was living in the house the bank told her she could afford.
This happens constantly. The lending industry’s definition of “affordable” and your actual ability to live comfortably inside a mortgage payment are two wildly different numbers. The gap between them gets even wider when you factor in retirement savings, healthcare costs, and the reality that your highest-earning years have a definite expiration date.
This piece breaks down the real math — not the lender’s math — so you can figure out what a house should actually cost you given where you are in life and where you need to be financially when you stop working.
How Banks Decide What You Can Afford (And Why It’s Wrong for You)
Mortgage lenders use a metric called the debt-to-income ratio (DTI) to determine how much they’re willing to lend you. The standard framework is the 28/36 rule: your monthly housing payment (principal, interest, taxes, insurance — often called PITI) should not exceed 28% of your gross monthly income, and your total monthly debt obligations should stay under 36%.
Sounds reasonable. The problem is what the formula leaves out.
What DTI ignores
- Retirement contributions. Your 401(k) and IRA deposits are invisible to the DTI calculation. The bank doesn’t care whether you’re saving 15% of your income for retirement or 0%.
- Healthcare costs. If you’re self-employed or buying individual coverage, premiums of $800–$1,500/month for a family don’t factor into the debt ratio.
- Property maintenance. The general rule is 1–2% of a home’s value per year in maintenance. On a $400,000 house, that’s $4,000–$8,000 annually — money the lender doesn’t account for.
- Future income decline. If you’re 52 and plan to retire at 65, the bank qualifies you on today’s salary. It doesn’t model what happens when that salary drops to zero.
The bank’s job is to determine whether you can make the payment. Your job is to determine whether you can make the payment and still build the life you want after work ends.
The adjusted rule for people thinking about retirement
Many certified financial planners, including those at the National Endowment for Financial Education, suggest a modified framework for buyers over 45 or anyone within two decades of retirement:
- Housing costs: 20–25% of gross income (not 28%)
- Total debt: 30% of gross income (not 36%)
- Retirement savings rate maintained at 15%+ regardless of the mortgage
That lower ceiling accounts for the reality that you need every remaining earning year to work double duty — funding your current life and funding the 20–30 years of life that come after your last paycheck.
The Rate Environment Changes Everything
Mortgage rates are the single biggest variable in housing affordability that you cannot negotiate, optimize, or hustle your way around. When rates move, your purchasing power moves with them — in the opposite direction.
Here’s what the same $2,200/month payment (principal and interest only) buys you at different rate levels on a 30-year fixed mortgage:
| Mortgage Rate | Home Price You Can Finance | Total Interest Paid Over 30 Years |
|---|---|---|
| 4.5% | ~$434,000 | ~$367,000 |
| 5.5% | ~$387,000 | ~$411,000 |
| 6.5% | ~$349,000 | ~$453,000 |
| 7.0% | ~$331,000 | ~$474,000 |
| 7.5% | ~$315,000 | ~$494,000 |
The difference between a 4.5% rate and a 7.5% rate is not trivial — it’s nearly $120,000 in purchasing power on the exact same monthly payment. And the total interest gap over the life of the loan is staggering: $127,000 more in interest at 7.5% compared to 4.5%.
According to Freddie Mac’s Primary Mortgage Market Survey, rates have been volatile throughout 2025 and into 2026, hovering in a range that makes the middle rows of that table the most relevant for current buyers.
Why “buy now, refinance later” isn’t always the answer
You’ll hear this advice constantly: lock in the house at today’s rate, then refinance when rates drop. It’s not bad advice in theory, but it carries assumptions people don’t examine:
- Rates might not drop meaningfully for years. The Federal Reserve has made clear that its rate decisions depend on inflation data, not buyer sentiment.
- Refinancing costs money. Closing costs on a refi typically run 2–5% of the loan amount. On a $350,000 mortgage, that’s $7,000–$17,500.
- You need sufficient equity. If home values stall or dip, you might not have the loan-to-value ratio required to refinance favorably.
- You’re making the high payment in the meantime. Every month you pay the elevated rate is a month you’re not investing that difference elsewhere.
The “refinance later” strategy works best when you’re buying a house you can genuinely afford at the current rate — not one you can only afford at a hypothetical future rate.
Running the Real Numbers: A Step-by-Step Affordability Check
Forget the online calculators that ask for your income and spit out a number. Here’s a more honest process.
Step 1: Start with your take-home pay, not gross income
Banks use gross income. You should use net — what actually hits your bank account after taxes, health insurance, and retirement contributions. If you earn $95,000 gross but take home $5,400/month after a 15% 401(k) contribution and standard deductions, $5,400 is your working number.
Step 2: Subtract your non-negotiable monthly obligations
These are the bills that don’t go away when you buy a house:
- Car payments
- Student loans
- Insurance premiums (auto, life, disability)
- Child support or alimony
- Minimum credit card payments
- Recurring medical costs
- Any other fixed debts
If these total $1,200/month, you’re down to $4,200 of usable income.
Step 3: Protect your future self
Before you allocate a dollar to housing, make sure these are funded:
- Emergency fund contributions — if you’re not at 6 months of expenses, keep building it
- Additional retirement savings beyond what’s already deducted — Roth IRA contributions, taxable brokerage, HSA
- Children’s education savings — 529 plans or equivalent
If these run $500/month, you’re now at $3,700.
Step 4: Apply a conservative housing ratio
Take 60–65% of what remains — not all of it, because you still need to eat, buy gas, and occasionally enjoy your life. That gives you roughly $2,200–$2,400/month for total housing costs.
And total means total: principal, interest, property taxes, homeowner’s insurance, PMI if applicable, HOA fees, and a maintenance reserve of roughly $300–$500/month depending on the home’s age and size.
Step 5: Back into the purchase price
With $2,200/month for PITI at a 6.5% rate, 1.2% property tax rate, and $150/month for insurance, your supportable mortgage is roughly $280,000–$300,000. Add your down payment, and that’s your realistic purchase price.
Notice how different this number is from what a lender would approve at the same income level. The bank might say $420,000. The math that protects your retirement says $340,000 with a $40,000–$60,000 down payment.
The Retirement-Specific Trap: Buying Too Much House Too Late
There’s a particular pattern that derails retirement plans, and it’s worth calling out directly. People in their late 40s and 50s — peak earning years, kids leaving, equity from a previous home — often “upgrade” to a larger or nicer house right when they should be accelerating savings.
The Employee Benefit Research Institute has consistently found that housing costs are the largest single expense for Americans over 65, consuming roughly a third of total spending for retirees who still carry a mortgage. Those who enter retirement mortgage-free spend dramatically less and report significantly higher financial confidence.
The math of a late-career mortgage
If you take a 30-year mortgage at age 53, you’re carrying that payment until age 83. If you take a 15-year mortgage at the same age, the payments are substantially higher but you’re free at 68 — three years into a typical retirement.
| Scenario | Loan Amount | Rate | Monthly Payment | Mortgage-Free Age | Total Interest |
|---|---|---|---|---|---|
| 30-year at age 53 | $300,000 | 6.5% | $1,896 | 83 | ~$382,000 |
| 15-year at age 53 | $300,000 | 5.9% | $2,509 | 68 | ~$152,000 |
| 20-year at age 53 | $300,000 | 6.2% | $2,186 | 73 | ~$225,000 |
The 15-year option costs $613 more per month but saves $230,000 in interest and gets you out from under the payment before your income drops. That $613/month difference is real money — but so is $230,000 in interest paid during your retirement years.
If you’re buying a house after 50, a shorter loan term isn’t just a nice-to-have. It’s a retirement planning decision that deserves as much attention as your asset allocation.
Where This Advice Does NOT Work
Honesty matters more than a tidy narrative, so here are the situations where the conservative approach above breaks down or needs serious modification:
- High cost-of-living metro areas. If you live in the San Francisco Bay Area, New York metro, or greater Boston, the “keep housing under 25% of gross” rule may be physically impossible without a two-hour commute. In these markets, the trade-off analysis shifts toward total compensation, rental parity, and long-term equity building. There’s no clean formula.
- If you’re already behind on retirement savings. Spending less on a house doesn’t help if the freed-up money goes to lifestyle inflation. The housing budget reduction only works if it’s paired with an automatic sweep of the difference into retirement accounts.
- Dual-income households where one income is uncertain. Freelancers, commission-based workers, or households where one partner might leave the workforce for caregiving should qualify themselves on the lower or more stable income alone.
- People who expect a significant inheritance or windfall. Counting money you don’t have yet as part of your housing budget is how people end up in foreclosure proceedings. Windfalls belong in the plan only after they arrive.
- Very early career buyers (under 30). If you’re decades from retirement and buying a starter home, you can afford to use closer to the standard 28/36 rule because time is on your side. The conservative framework above is calibrated for buyers in mid-career and beyond.
The common mistake across all of these: treating the maximum amount a bank will lend as a spending target rather than a ceiling you should stay well below.
Strategies That Actually Move the Needle
Rather than agonizing over rate predictions or timing the market, focus on the variables you control.
Make a larger down payment — but not from retirement accounts
Every dollar of down payment reduces your loan amount, your monthly payment, and your total interest. Aim for 20% to avoid private mortgage insurance (PMI), which adds $100–$300/month on a typical loan and provides zero benefit to you.
But — and this is critical — do not raid your 401(k) or IRA to fund a down payment unless you’ve run the numbers with a financial advisor. The tax penalties, lost compounding, and reduced retirement runway almost never justify the savings on PMI.
Consider the 15-year mortgage seriously
Yes, the payment is higher. But if you can swing it, the interest savings are enormous and you enter retirement without a housing payment. Even if you can’t quite afford the 15-year payment, making a 30-year payment with occasional extra principal payments accomplishes a similar goal with more flexibility.
Buy less house than you qualify for
This is the simplest and most effective strategy, and the hardest one emotionally. The 2,400-square-foot house with the updated kitchen is appealing. The 1,800-square-foot house that leaves room in your budget for maxing out your IRA is less exciting to walk through — but dramatically more exciting at age 67 when your savings are intact.
Location arbitrage for pre-retirees
If you’re within 10 years of retirement and not tied to a specific metro area by employment, buying in a lower cost-of-living area can be the single highest-impact financial decision you make. The same budget that buys a modest condo in a major city can purchase a comfortable home outright in many mid-size markets. Resources like the Bureau of Labor Statistics’ Consumer Expenditure Survey can help you compare regional cost differences.
🔑 Key Takeaways
- What the bank approves and what you can actually afford are two very different numbers — use net income and protect retirement savings before calculating your housing budget.
- Each percentage point of mortgage rate increase reduces buying power by roughly 10%, making rate-aware budgeting essential.
- Buyers over 45 should target housing costs at 20–25% of gross income (not the standard 28%) to preserve retirement savings runway.
- A 15-year mortgage or aggressive extra payments can save six figures in interest and eliminate housing costs before retirement.
- Buying less house than you qualify for is the single most reliable strategy for long-term financial health.
Frequently Asked Questions
What is the 28/36 rule and should I follow it?
The 28/36 rule is the lending industry’s standard: spend no more than 28% of gross monthly income on housing and no more than 36% on total debt. It’s a useful baseline, but it was designed to assess default risk for lenders — not to optimize your financial life. If you’re within 15–20 years of retirement, most planners recommend tightening those numbers to 20–25% and 30%, respectively, to leave room for the savings growth you still need.
How do current mortgage rates affect how much house I can afford?
Rates are the biggest lever in the affordability equation. When rates rise from 5% to 7%, a buyer who could afford a $400,000 home at the lower rate can only support roughly $330,000–$340,000 at the higher one, assuming the same income and down payment. The monthly payment stays the same, but the loan amount it supports shrinks considerably. This is why rate-shopping across multiple lenders — even a quarter-point difference matters — should be a non-negotiable part of your buying process. Check out our guide on maximizing your retirement portfolio for more on balancing housing with investment goals.
Should I wait for mortgage rates to drop before buying a home?
Trying to time the rate market is like trying to time the stock market — professionals get it wrong regularly. If you find a home that fits your conservative budget at today’s rates, buying now and refinancing later if rates drop significantly is usually the more practical path. The risk of waiting is that home prices rise while you sit on the sidelines, offsetting or exceeding any rate savings. We covered this dynamic in detail in our piece on understanding the housing market cycle.
How much of my retirement savings should go toward a down payment?
As little as possible. Financial advisors typically caution against pulling more than 10–15% of your retirement portfolio for a home purchase, and many argue the number should be zero. Withdrawals from traditional retirement accounts before age 59½ trigger a 10% early withdrawal penalty on top of income taxes. Even after 59½, the lost compounding on withdrawn funds can cost you far more over time than the PMI or higher payment you were trying to avoid. Build your down payment from current savings, not from your future self’s nest egg.
Making the Right Call
The housing decision is, for most people, the largest financial commitment they’ll ever make — and the one with the longest tail. Getting it right doesn’t require perfection or a crystal ball on rates. It requires honesty about the gap between what a bank will lend you and what your actual financial life can support, especially when retirement is on the horizon. Run the math using your net income, protect your savings rate, and buy a home you’ll enjoy living in without dreading the monthly payment. If you’re looking for a broader framework, our complete retirement planning checklist walks through every piece of the puzzle beyond housing. The house is just one line item — make sure it doesn’t crowd out the rest.
Mortgage rate examples and payment calculations use standard amortization formulas. Actual rates, taxes, insurance, and fees vary by location, lender, and borrower profile. Consult a licensed mortgage professional and a fiduciary financial advisor before making purchase decisions.