"Don't pay off your mortgage — you'll lose the tax deduction" is one of the most repeated pieces of financial advice in America. For most homeowners today, it is simply wrong. Here is how the deduction actually works, why the majority of borrowers get nothing from it, and how that changes the extra-payment decision.
How the deduction works
The home mortgage interest deduction lets you deduct interest paid on "acquisition debt" — a loan used to buy, build, or substantially improve your main or second home — but only if you itemize deductions on Schedule A instead of taking the standard deduction. The key rules (see IRS Publication 936):
- Interest is deductible on up to $750,000 of acquisition debt for loans taken out after December 15, 2017 ($1 million for older loans; $375,000 / $500,000 if married filing separately).
- Home equity loan or HELOC interest is deductible only if the funds were used to buy or improve the home securing the loan — not for other spending.
- You can only deduct interest you actually paid during the tax year, reported to you on Form 1098.
Why most homeowners no longer benefit
The 2017 tax law roughly doubled the standard deduction and capped the state-and-local-tax (SALT) deduction. The result: the large majority of taxpayers — commonly cited as around 90% — now take the standard deduction, because their itemizable expenses do not add up to more than it.
You only get value from the mortgage interest deduction to the extent your total itemized deductions exceed the standard deduction. If itemizing would give you $28,000 in deductions and the standard deduction is $29,000, your mortgage interest produced zero tax benefit — you would take the $29,000 either way.
A quick example
Married couple, filing jointly. Suppose the standard deduction is $30,000 (check the current-year figure — it is indexed for inflation).
| Itemized deduction | Amount |
|---|---|
| State and local taxes (SALT, capped) | $10,000 |
| Mortgage interest | $14,000 |
| Charitable gifts | $3,000 |
| Total itemized | $27,000 |
Here, itemizing ($27,000) is less than the standard deduction ($30,000), so this couple takes the standard deduction and their $14,000 of mortgage interest saves them nothing in tax. Paying the mortgage down faster costs them no tax benefit at all.
Now suppose their mortgage interest is $24,000 (a larger or newer loan). Total itemized becomes $37,000 — $7,000 above the standard deduction. Only that $7,000 "extra" is doing any work. In a 22% bracket, it is worth about $1,540 — and it shrinks every year as the loan amortizes and the interest portion falls.
What this means for paying extra
- If you take the standard deduction (most people): your mortgage rate is your true, effective cost of borrowing. A 6.5% loan costs you 6.5%. The "guaranteed return" from prepaying is the full rate.
- If you itemize and your interest clears the standard deduction: your effective after-tax rate is lower. A 6.5% loan for someone in the 24% bracket, whose interest is fully "above" the standard deduction, has an effective cost closer to 6.5% × (1 − 0.24) ≈ 4.9%. That makes investing relatively more attractive — see pay off early vs. invest.
- The benefit is front-loaded and fading. Early in a loan, interest — and any deduction — is largest. As you pay down principal (or pay extra), interest falls and the deduction, if you were getting one, shrinks toward zero.
Bunching: getting the deduction back some years
If you are just below the itemizing threshold, some households "bunch" deductible expenses — for example, making two years of charitable gifts in one calendar year (often through a donor-advised fund) — so they itemize every other year and take the standard deduction in between. Mortgage interest is not something you can time this way, but it can push a near-threshold return over the line in bunching years.
The mortgage payoff and property taxes
One real change when you pay off a mortgage: if your loan had an escrow account, you become responsible for paying property taxes and homeowners insurance directly, on their schedule. Budget for those bills — they do not go away, they just stop being bundled into a monthly payment. Property taxes remain part of the SALT deduction (still capped) whether or not you have a mortgage.
Effective after-tax rate, by bracket
This only applies to interest that is fully above your standard deduction — the marginal, deductible dollars. For those dollars, the effective rate is the stated rate × (1 − your marginal federal rate). Illustrative, federal only:
| Stated mortgage rate | 12% bracket | 22% bracket | 24% bracket | 32% bracket |
|---|---|---|---|---|
| 3.0% | 2.64% | 2.34% | 2.28% | 2.04% |
| 5.0% | 4.40% | 3.90% | 3.80% | 3.40% |
| 6.5% | 5.72% | 5.07% | 4.94% | 4.42% |
| 7.5% | 6.60% | 5.85% | 5.70% | 5.10% |
If your state has an income tax that also allows the deduction, the effective rate is a little lower still. But remember: if your interest does not clear the standard deduction, none of this applies and your effective rate equals the stated rate.
Other homeownership deductions people confuse with mortgage interest
- Property taxes are deductible, but only as part of the SALT category, which is capped (state income/sales tax + property tax combined). Many homeowners hit the cap on state income tax alone, leaving property tax with no marginal benefit.
- Points paid on a purchase loan are generally deductible in the year paid; points on a refinance must usually be deducted gradually over the life of the loan.
- Private mortgage insurance (PMI): the deduction for PMI premiums has lapsed and been revived several times by Congress. Check whether it applies for the current tax year on irs.gov.
- Homeowners insurance, HOA dues, and principal payments are never deductible on a personal residence.
The $750,000 limit and mixed-date debt
The $750,000 acquisition-debt cap applies to loans taken out after December 15, 2017. Loans originated on or before that date keep the older $1,000,000 cap, as long as they are not refinanced for more than the remaining balance. If you have both older and newer acquisition debt, the limits interact — Publication 936 has a worksheet. Above the applicable limit, only the share of interest attributable to the deductible portion of the balance counts.
Married filing separately
The acquisition-debt limit is halved ($375,000 for post-2017 debt), and if one spouse itemizes, the other generally must itemize too — they cannot take the standard deduction. Couples close to the itemizing threshold should run it both ways.
What happens to the tax picture when you pay the loan off
- Your Form 1098 interest drops to zero, so any deduction you were getting ends. If that was pushing you over the standard deduction, you now simply take the standard deduction.
- Property taxes remain deductible (still within the SALT cap) whether or not you have a mortgage — you just pay them directly instead of through escrow.
- Paying off the mortgage has no effect on the capital-gains exclusion when you sell ($250,000 single / $500,000 married on a primary residence you have owned and lived in for 2 of the last 5 years). The exclusion is based on gain, not on whether the home is financed.
Bottom line
Do not keep a mortgage solely "for the deduction." First check whether you itemize at all. If you take the standard deduction, the deduction is irrelevant to your decision and your mortgage rate is your real cost. If you do itemize, calculate how much of your interest is actually above the standard deduction — only that portion lowers your effective rate. Then run the payoff math on our calculator and weigh it against investing in pay off early vs. invest.