A 30-year mortgage is not inherently a bad decision, but it is an expensive one: on a $300,000 loan at current rates, you would pay roughly $208,000 more in interest than you would on a 15-year loan. Whether that extra cost is worth it depends on how long you plan to keep the house, whether you will actually put the lower monthly payment to productive use, and how stable your income is. The short answer to the question “is a 30-year mortgage bad” is that it’s a bad fit for some situations and a sensible choice for others.
What the Longer Term Actually Costs You
As of early 2026, the average 30-year fixed rate sits around 6.00%, compared with 5.43% on a 15-year fixed.1Freddie Mac. Primary Mortgage Market Survey (PMMS) Results Borrow $300,000 for 30 years at 6.00% and the interest alone runs about $347,500, pushing the total cost of the loan to roughly $647,500. The same $300,000 at 5.43% over 15 years generates about $139,000 in interest, for a total of about $439,000. The 30-year borrower pays about $208,000 more for the privilege of stretching repayment out twice as long.
Two things drive that gap. The rate itself is slightly higher on the longer term, and every dollar of principal sits on the lender’s books longer, accruing interest the entire time. The amortization schedule shows the effect clearly. On that $300,000 loan, your first monthly payment of about $1,799 sends roughly $1,500 to interest and only $299 to principal. It takes well over a decade before the split approaches fifty-fifty. The lender has to disclose this cumulative interest in your closing documents before you sign.2Consumer Financial Protection Bureau. 12 CFR Part 1026 Regulation Z – Section 1026.17 General Disclosure Requirements
Why Most Buyers Still Pick the 30-Year
The lower monthly payment is the whole reason this loan dominates the market. That $300,000 at 6.00% over 30 years costs about $1,799 per month in principal and interest. The 15-year version runs about $2,440. The roughly $640 monthly difference is often the line between qualifying for a home and not.
Lenders look at your debt-to-income ratio, which is your total monthly debt payments divided by gross monthly income.3Consumer Financial Protection Bureau. What Is a Debt-to-Income Ratio? A smaller payment keeps that ratio down, which either helps you qualify at all or lets you buy a bigger home. The CFPB recommends keeping total DTI at 36% or below, though many lenders will approve higher.4Consumer Financial Protection Bureau. Debt-to-Income Calculator Tool
The lower required payment also works as built-in protection against financial shocks. Your contract sets the minimum, not the maximum. Federal law prohibits prepayment penalties entirely on non-qualified residential loans, and on qualified mortgages any penalties are capped and disappear after the first three years.5Office of the Law Revision Counsel. 15 USC 1639c – Minimum Standards for Residential Mortgage Loans In practice, most standard 30-year fixed loans have no prepayment penalty at all. You can throw an extra $500 at principal in a good month and fall back to the minimum when a job ends or the furnace dies. The 15-year borrower locked into a payment $640 higher every month doesn’t have that flexibility.
When a 30-Year Mortgage Is a Bad Idea
If you expect to sell within five to seven years, the slow equity build on a 30-year loan is a real problem. After five years of payments on that $300,000 loan at 6%, you’ve knocked only about $21,000 off the balance, roughly 7% of what you borrowed. A 15-year borrower at 5.43% has paid down about $75,000 over the same five years, retiring a quarter of the debt.1Freddie Mac. Primary Mortgage Market Survey (PMMS) Results
That gap matters at the closing table. After you subtract the remaining loan balance, broker commissions, and closing costs, a 30-year borrower selling in year five may walk away with almost nothing unless the home has appreciated meaningfully. If prices stayed flat or dipped, you can end up owing more than you net. The 15-year borrower has a much larger equity cushion against that outcome.
The 30-year is also a bad call if the payment difference will just dissolve into daily spending. The extra $208,000 in interest only makes strategic sense if the freed-up cash is doing something productive. Paying $208,000 more so you can eat out more often is not a financial strategy.
When the Math Actually Favors the 30-Year
The standard advice says less interest is always better. That logic ignores what you could do with the monthly savings. If you take the 30-year loan and consistently invest the $640 difference, the long-term result may favor the longer loan.
The S&P 500 has returned roughly 10% annually over 30-year windows historically, and about 7.6% after inflation. A 30-year mortgage at 6% costs you 6% on the borrowed money. If your investments outearn your mortgage rate over time, the longer loan effectively pays you despite the higher total interest. The catch is real: investment returns aren’t guaranteed, and the market doesn’t move in a straight line. A decade of flat returns at the wrong moment can wreck the comparison.
The comparison isn’t quite “invest the difference for 30 years” either. The 15-year borrower is debt-free at year 15 and can redirect the entire former payment into investments after that. The 30-year path offers a smaller investment stream over more years; the 15-year path offers no investment stream during payoff and a much larger one after. Which wins depends on when returns show up and what tax bracket you’re in. The flexibility argument still carries weight: $640 a month you choose to invest is a different thing from $640 you must pay a lender.
Inflation Quietly Helps the Longer Loan
A fixed payment gets lighter in real terms as prices and wages rise. A $1,799 payment feels heavy today. In twenty years, under even moderate 2–3% annual inflation, that same dollar amount represents a far smaller share of a typical household income. Over three decades the real burden can fall by roughly half. A 15-year loan is paid off before inflation has much time to work on your behalf, which narrows the effective interest gap between the two terms. The effect depends on wages keeping pace with inflation; if your income stagnates while prices rise, the fixed payment still helps, but the broader picture does not improve as much.
PMI Hits 30-Year Borrowers Harder
If you put less than 20% down on a conventional loan, you’ll pay private mortgage insurance, and PMI costs 30-year borrowers more because the balance drops more slowly. PMI typically runs $30 to $70 per month per $100,000 borrowed.6Freddie Mac. Breaking Down PMI On a $300,000 loan, that’s an extra $90 to $210 per month that neither builds equity nor cuts your balance.
Under the Homeowners Protection Act, you can request PMI cancellation once your balance reaches 80% of the home’s original value.7Office of the Law Revision Counsel. 12 USC 4901 – Definitions Reaching that 80% mark on a 30-year loan through scheduled payments alone takes roughly nine to eleven years. A 15-year borrower gets there in about four to five. If you don’t ask, your servicer must terminate PMI automatically when the scheduled balance hits 78% of original value.8Office of the Law Revision Counsel. 12 USC 4902 – Termination of Private Mortgage Insurance Extra principal payments or a new appraisal showing enough appreciation can speed cancellation, but you have to take the step.
Don’t Count on the Tax Deduction to Rescue It
A 30-year loan generates more interest, which means more potential savings through the mortgage interest deduction. You can deduct interest on up to $750,000 of mortgage debt used to buy, build, or substantially improve your home ($375,000 if married filing separately).9Internal Revenue Service. Publication 936 – Home Mortgage Interest Deduction That limit was made permanent under the One, Big, Beautiful Bill Act signed in 2025, which also made PMI premiums deductible as mortgage interest starting in 2026.
The deduction only helps if you itemize. The 2026 standard deduction is $32,200 for married couples filing jointly, $16,100 for single filers, and $24,150 for heads of household.10Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 A married couple with a $300,000 mortgage at 6% pays about $18,000 in interest the first year. Combined with state and local taxes and charitable giving, many borrowers still won’t clear $32,200. Borrowers with loans closer to the $750,000 cap, or those in high-tax states, are more likely to benefit. Taking a 30-year loan specifically for the tax deduction is backwards reasoning for most people. You don’t come out ahead by paying $18,000 in interest to recover a few thousand in taxes. The deduction softens the cost; it doesn’t flip the sign.
Refinancing Gives You an Exit
A 30-year mortgage doesn’t have to stay a 30-year mortgage. If rates drop meaningfully after you close, refinancing into a lower rate or a shorter term can recover much of the interest you’d otherwise pay. The math is simple: divide total closing costs by the monthly savings from the new rate, and the answer is how many months it takes to break even. Stay longer than that, and refinancing saves you money.
Refinance closing costs typically run 3% to 6% of the new loan amount, covering appraisal, title insurance, origination, and the rest. On a $280,000 remaining balance, that’s $8,400 to $16,800 upfront. If the new rate drops your payment by $300, the break-even sits at 28 to 56 months. Everything after that is savings.
You can also refinance from a 30-year into a 15-year later, once your income has grown enough to handle the higher payment. Starting with the 30-year preserves cash-flow room early while leaving the shorter-term option open. This staged approach won’t beat someone who locks in a 15-year on day one and never wavers, but most financial lives don’t run in a straight line.
So Is It Bad for You?
A 30-year mortgage is a reasonable fit if you plan to stay in the home long enough for inflation to work in your favor, if you’ll actually invest the monthly savings instead of absorbing them into spending, or if the lower payment is the difference between owning and renting indefinitely. It also makes sense when your income is variable and you need the safety net of a smaller required payment.
It’s a poor fit if you plan to sell within five to seven years, because slow equity accumulation leaves you with little to show for years of payments. It’s also the wrong choice if the extra cash flow will quietly become lifestyle creep.
If you can comfortably afford the 15-year payment and have no better use for the cash, the shorter term saves a large amount of money with no investment risk required. For everyone else, a 30-year loan combined with disciplined extra principal payments or consistent investing is a defensible way to buy a home.