The §163(h)(3) dollar limits are statutory, permanent, and not indexed for inflation. The year changes the SALT cap context and the assumptions table.
MFS: $375,000 / $500,000 limits. IRC §163(h)(3)(B)(ii) and (F)(i)(II).
Used only for the mortgage insurance premium phase-out. IRC §163(h)(3)(E)(ii).
2
Primary Mortgage
Loan 1 - Main home or first mortgage
Binding-contract exception: a written contract signed before December 15, 2017 to close on a principal residence before January 1, 2018, with the purchase completed before April 1, 2018, uses the December 15, 2017 tier. IRC §163(h)(3)(F)(i)(V).
Form 1098, Box 2 shows only the January 1 principal. Use the average of first and last balance, monthly averages, or the highest balance. Pub. 936, Average Mortgage Balance.
Form 1098, Box 1. Do not include points or mortgage insurance premiums.
Home acquisition debt only. Cash-out proceeds used for other purposes are not acquisition debt, and their interest is not qualified residence interest for tax years beginning after 2017. IRC §163(h)(3)(B) and (F)(i)(I). Ignored for loans from October 13, 1987 or earlier.
3
Additional Mortgages / HELOC (Optional)
Loan 2
Enter 0 for a HELOC or second mortgage used for non-home purposes. IRS Notice 2018-32.
Loan 3
Refinancing: debt that refinances older debt is treated as incurred on the original date, but only up to the old principal balance, and only for the remaining term of the original loan (30 years if it was not amortizing). Enter the refinanced balance under the original date and any cash-out as a separate loan. IRC §163(h)(3)(F)(ii). The $1M and $750K limits apply to the combined debt on the main home and one second home.
4
Mortgage Insurance Premiums
Form 1098, Box 5. Qualified mortgage insurance is VA, FHA, or RHS insurance and private mortgage insurance under contracts issued after December 31, 2006, in connection with acquisition debt. Treated as qualified residence interest for tax years beginning after December 31, 2025. IRC §163(h)(3)(E), (F)(i)(III); OBBBA §70108.
5
Deduction Analysis
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Last verified: October 29, 2026
Projected figures are estimates and are not IRS-published. Every parameter used by this calculator is either fixed by statute or published by the IRS, so no projected amounts are used. Results are estimates for planning only.
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