Mortgage Interest Deduction Rules for 2026

TL;DR: The mortgage interest deduction is capped at loans up to $750K for post-2017 mortgages, and only helps if your total itemized deductions exceed the standard deduction.

_Last reviewed: July 2026 · 4 min read_

If you're wondering how much of your mortgage interest you can actually deduct on your 2026 return, the honest answer is: only if you itemize AND your loan qualifies AND the total tops the standard deduction. For most homeowners with post-2017 mortgages, the interest deduction alone isn't enough to beat the standard deduction — but combined with property tax (up to $10K SALT cap) and charitable giving, it often does.

Okoniq Property Hub stores your mortgage interest annual statement (Form 1098) alongside property tax + insurance records so the year-end tax picture is one screen.

What loans qualify?

To deduct mortgage interest, the loan must be secured by a qualified home (your primary or one other second home) AND be one of:

• Acquisition debt — used to buy, build, or substantially improve the home
• Home equity debt — under pre-2017 rules only; post-2017, home equity interest is deductible ONLY if the funds were used for acquisition-type purposes

The distinction matters because home equity debt used for non-home purposes (paying credit cards, buying a car, funding a vacation) is NOT deductible on 2018+ returns.

Full rules are in IRS Publication 936 (Home Mortgage Interest Deduction).

What are the loan caps?

Depends on when your mortgage originated:

• Loans originated after 12/15/2017: interest deductible on acquisition debt up to $750,000 ($375K if married filing separately).
• Loans originated before 12/16/2017: grandfathered — interest deductible on acquisition debt up to $1,000,000 ($500K MFS).
• Refinances of pre-2018 loans generally keep the $1M cap if the new loan doesn't exceed the old balance and isn't otherwise "substantially modified."

If your loan balance exceeds the cap, you deduct the interest attributable to only the portion within the cap.

What about HELOCs and home equity loans?

HELOC interest is deductible ONLY IF the funds were used to buy, build, or substantially improve the home securing the loan. Using a HELOC to consolidate credit card debt or fund a college education = not deductible for federal tax.

The cap ($750K post-2017, $1M pre-2018) is on TOTAL acquisition debt — so a first mortgage of $600K plus a HELOC used for a kitchen remodel of $100K is fully within the cap. See HELOC vs cash-out refinance for the acquisition-debt comparison.

When does mortgage interest actually help my return?

Only if you itemize. The 2026 standard deduction is roughly $15,700 single / $31,400 married filing jointly (subject to IRS annual adjustment).

To beat the standard deduction, your total itemized needs to exceed those amounts. Common itemized categories:

• Mortgage interest — from Form 1098
• State and local taxes (SALT) — capped at $10,000 per return (property tax + state income tax + sales tax)
• Charitable contributions — cash + non-cash
• Medical expenses — above 7.5% of AGI
• Casualty losses — federally-declared disaster only

Example: married couple with $12K mortgage interest + $10K SALT (capped) + $5K charitable = $27K itemized. Beats the $31.4K standard deduction? No — they take the standard.

Same couple with $18K mortgage interest + $10K SALT + $8K charitable = $36K. Now itemizing wins.

What about landlords?

For rental properties, mortgage interest goes on Schedule E with no cap, no SALT limit, no standard-deduction threshold. It's a straight rental expense against rental income. This is one of the reasons rentals often show paper losses (see passive loss $25K allowance).

Keep your 1098 with the tax file

The mortgage interest deduction is one of the simplest calculations — you enter the Form 1098 total on Schedule A — but only if you have the 1098 handy. Okoniq Property Hub stores the annual Form 1098 alongside every other tax document per property. Related: Schedule E deductions in 2026, homestead vs property tax exemption, and the Taxes & Accounting hub.

Frequently asked questions

What if I refinanced?

Interest on a refinance is deductible under the same rules as the original loan (grandfathered $1M cap survives if pre-2018 loan is refinanced without increasing principal). Cash-out portion is subject to the post-2017 $750K cap on the cash-out amount.

Are points deductible?

Points paid on the purchase of your primary residence are generally deductible in the year paid. Points on a refinance are typically amortized over the life of the loan.

Do second homes count?

Yes — one designated second home also qualifies for the mortgage interest deduction, sharing the same cap. Third homes and beyond don't qualify.

Not tax advice. Mortgage interest deduction interacts with itemization, SALT caps, and refinance rules in nuanced ways — consult a CPA if in doubt. Okoniq Property Hub keeps the documents ready. Get started free.

FAQ

Can I deduct mortgage interest if I don't itemize my taxes?

No — the mortgage interest deduction is only available if you itemize deductions on Schedule A, and only if your total itemized deductions exceed the standard deduction ($15,700 single / $31,400 married filing jointly for 2026).

Does the $750,000 mortgage cap apply separately to each spouse?

No — the $750,000 cap applies per tax return, not per person, so married couples filing jointly share the same $750,000 limit (or $375,000 each if filing separately).

What happens to my mortgage interest deduction if my loan balance is exactly $800,000?

You deduct only the portion of interest attributable to the first $750,000 — your lender's Form 1098 shows total interest paid, and you calculate the deductible fraction as $750K ÷ $800K, then multiply that percentage by the total interest.

Is mortgage interest on a rental property subject to the $750,000 cap?

No — rental property mortgage interest is reported on Schedule E as a rental expense with no dollar cap and no requirement to itemize, making it fully deductible against rental income regardless of loan size.