Homeowner tax benefit estimator
HiddenHomeCost shows what a house really costs each month. This shows the other side of the ledger: the first-year mortgage-interest and property-tax deductions, what they save in federal and California income tax, and what that is worth per month.
Agents: run this with a buyer and hand them the PDF. Open "Prepared by" below to put your name, brokerage and DRE on the report — it is remembered on this device for next time.
HiddenHomeCost exists to show what a home actually costs every month — the property tax rate for that parcel, the Mello-Roos nobody mentioned, the fire-zone insurance, the utility territory. This page is the other direction. Two of those same costs, the mortgage interest and the property tax, can be itemized deductions that lower taxable income. In the early years of a loan almost every dollar of the payment is interest, so the deduction is largest exactly when a new buyer feels the payment most.
For a loan taken out after December 15, 2017, federal law limits the mortgage-interest deduction to the interest on the first $750,000 of loan balance ($375,000 married filing separately). Above that, only part of the interest is federally deductible — a detail plenty of buyers get wrong on a jumbo loan. California is more generous and still allows interest on up to $1,000,000, so the state deduction is often the larger of the two.
Property tax is deductible, but it shares one state-and-local-tax bucket with the state income tax already being paid. For 2025 that bucket is capped at $40,000 ($20,000 married filing separately), with a phase-down at higher incomes — in California it is easy to reach, so the calculator applies it the way a return would. Homeowner insurance is never deductible. Neither are HOA dues. And Mello-Roos is the one to be careful with: a special assessment that funds a specific district is generally not deductible even though it lands on the same tax bill, which is why it belongs in the cost column, not this one. If that applies to the address, the county hidden-cost guides cover which districts carry it.
Because these deductions lower the tax owed, many new homeowners are over-withholding from every paycheck the moment they buy. Adjusting the W-4 puts some of that back in the monthly budget instead of waiting on a refund — withhold too little, though, and there is a balance due at filing. The advanced option above uses W-2 figures to size that adjustment. Then run the address itself through the true-cost search to see the payment side, or read why HiddenHomeCost exists.
An educational estimate, not tax advice or a loan offer. Figures use 2025 federal and California tax law and the scenario entered. Consult a CPA about a specific situation.
For a loan taken out after December 15, 2017, federal law lets you deduct the interest on the first $750,000 of loan balance ($375,000 if married filing separately). California allows interest on up to $1,000,000. On a larger loan, only the share of interest tied to those limits is deductible.
No. Hazard insurance on a primary residence is not deductible. Only mortgage interest and property tax, within the SALT cap, reduce taxable income.
Generally no. A Mello-Roos special tax funds a specific community facilities district rather than a general levy on assessed value, so it usually is not deductible even though it appears on the same property tax bill. Confirm with a CPA for a specific parcel.
For 2025 the state-and-local-tax deduction is capped at $40,000 ($20,000 married filing separately), with a phase-down for incomes over $500,000. Property tax plus state income tax paid count toward this cap.
No. It produces an estimate from the scenario entered and 2025 federal and California tax law. It is not tax advice, not a loan offer, and not a commitment to lend. Confirm with a CPA.