Updated October 19, 2026. Quick answer: Publication 936 is the IRS guide to deducting home mortgage interest. The web edition is for 2025 returns. It says you can deduct interest on the first $750,000 of indebtedness ($375,000 if married filing separately), with higher limits for older debt.
Quick reference
| Item | As the IRS publication states it |
|---|---|
| Debt limit for mortgage interest (Reminders) | $750,000 ($375,000 if married filing separately) |
| Higher limit for debt incurred before December 16, 2017 (Reminders) | $1 million ($500,000 if married filing separately) |
| Grandfathered debt cutoff date (Fully deductible interest) | on or before October 13, 1987 |
| Points paid, initial principal amount test (Deduction Allowed Ratably) | $250,000 or less |
| Loan period for ratable points (Deduction Allowed Ratably) | not more than 30 years |
What the publication covers
The IRS publication says “This publication discusses the rules for deducting home mortgage interest.” “Part I contains general information on home mortgage interest, including points.” “Part II explains how your deduction for home mortgage interest may be limited.”
The edition described here is Publication 936 (2025), Home Mortgage Interest Deduction. The IRS source marks it with the line “For use in preparing 2025 Returns”.
The parts in plain words
Part I covers what counts as home mortgage interest: secured debt, a qualified home (main home, second home, divided use, home under construction, time sharing arrangements), special situations such as late payment charges and mortgage prepayment penalties, points, Form 1098, and the special rule for tenant stockholders in cooperative housing corporations. Part II covers the limits: home acquisition debt, grandfathered debt, and a worksheet for the qualified loan limit.
The tables and figures inside it
Figure A is a flowchart for whether home mortgage interest is fully deductible, and Figure B is a quick guide to whether points are deductible in the year paid. Table 1 is a worksheet to figure your qualified loan limit and deductible home mortgage interest, and Table 2 shows where to deduct other interest expense. The IRS publication says “Fill out only one Table 1 for both your main and second home regardless of how many mortgages you have.” On this site, the matching page is the home mortgage interest limit worksheet.
The figures that matter
Debt limit: “You can deduct home mortgage interest on the first $750,000 ($375,000 if married filing separately) of indebtedness.” “However, higher limitations ($1 million ($500,000 if married filing separately)) apply if you are deducting mortgage interest from indebtedness incurred before December 16, 2017.”
Grandfathered debt: the first of three categories is “Mortgages you took out on or before October 13, 1987 (called grandfathered debt).”
Home equity loans: “No matter when the indebtedness was incurred, you can no longer deduct the interest from a loan secured by your home to the extent the loan proceeds weren’t used to buy, build, or substantially improve your home.”
Mortgage insurance: “The itemized deduction for mortgage insurance premiums has expired.”
Points spread over the loan: the tests include “Your loan period isn’t more than 30 years.” and “Either the initial principal amount of your loan was $250,000 or less, or the number of points isn’t more than:”
Where to go next
Interest reported on Form 1098 goes to Schedule A line 8a. The statement itself is explained at Form 1098 box 1, box 2 and box 6 for points. The overall deduction sits on Schedule A (Form 1040).
Where this comes from
The IRS page About Publication 936 opens with “Publication 936 discusses the rules for deducting home mortgage interest.” It links the PDF and eBook editions and the earlier revisions of the publication.
This page describes the web edition of Publication 936 (2025), Home Mortgage Interest Deduction, as served on irs.gov on October 19, 2026. The IRS can revise a publication after we read it, and the IRS page controls. General information, not tax or legal advice.
Common mistakes
- Deducting interest on any loan secured by the home. The IRS publication says “The mortgage is a secured debt on a qualified home in which you have an ownership interest.”
- Treating home equity interest as always deductible. The publication says “No matter when the indebtedness was incurred, you can no longer deduct the interest from a loan secured by your home to the extent the loan proceeds weren’t used to buy, build, or substantially improve your home.”
- Assuming mortgage insurance premiums still count. The publication says “The itemized deduction for mortgage insurance premiums has expired.”
- Filling out a separate Table 1 for each mortgage. The publication says “Fill out only one Table 1 for both your main and second home regardless of how many mortgages you have.”
Related: IRS publications by number, Home mortgage interest limit worksheet, Schedule A line 8a, mortgage interest on Form 1098, Form 1098 box 1, Form 1098 box 6, points, Form 1098, and Schedule A (Form 1040).
Sources
- IRS, Publication 936 (2025), Home Mortgage Interest Deduction (irs.gov): https://www.irs.gov/publications/p936
- IRS, About Publication 936 (irs.gov): https://www.irs.gov/forms-pubs/about-publication-936
Read from the IRS pages linked above on October 19, 2026. General information, not tax or legal advice. The IRS publication and the instructions for your own form control, and your own facts decide the outcome.