The mortgage interest tax deduction is one of the most talked-about — and most misunderstood — aspects of US homeownership. Many buyers assume it provides a guaranteed, significant tax benefit. For a large share of homeowners, particularly since the standard deduction roughly doubled in 2018, that's no longer automatically true. This guide explains exactly how it works today.
Tax situations vary significantly by individual circumstances. This article explains the general framework — always consult a qualified tax professional for advice specific to your situation.
1. The short answer
Mortgage interest is deductible — but only if you itemise deductions rather than take the standard deduction, and only if your itemised deductions exceed what the standard deduction would give you automatically. For many homeowners today, the standard deduction is actually larger than their itemisable deductions, meaning the mortgage interest deduction provides no additional tax benefit at all.
2. Itemising vs the standard deduction
Every taxpayer can choose between two approaches: take the standard deduction (a fixed amount, no questions asked) or itemise specific deductible expenses if their total exceeds the standard amount. The Tax Cuts and Jobs Act of 2017 significantly raised the standard deduction starting in 2018, which means fewer homeowners benefit from itemising than in previous decades.
The basic comparison
No itemising needed. Same for everyone in your filing status.
Mortgage interest + state/local taxes (capped) + charitable giving + more.
You take whichever is higher. Check current standard deduction amounts at irs.gov, as figures are adjusted annually for inflation.
3. Current debt limits
Per IRS Publication 936, mortgage interest is deductible on up to $750,000 of mortgage debt for loans originated after December 15, 2017. For mortgages taken out before that date, the prior limit of $1 million generally still applies. These limits apply to the combined total of debt on your primary residence and one additional qualifying home.
4. What else counts toward itemised deductions
Mortgage interest doesn't stand alone — it's added to other itemisable expenses to determine your total. Common categories include:
- State and local taxes (SALT) — currently capped at $10,000 combined
- Charitable contributions
- Certain medical expenses exceeding a percentage-of-income threshold
- Mortgage points (under specific conditions, often in the year of purchase)
It's the combined total of all these categories that needs to exceed the standard deduction for itemising to provide any benefit.
5. Worked example — does it actually help Linda?
Linda's potential itemised deductions: $19,500 (mortgage interest) + $10,000 (SALT, capped) + $2,500 (charitable) = $32,000 total.
If the current standard deduction for a single filer is below $32,000, itemising clearly benefits Linda — she should itemise and claim the mortgage interest deduction.
If she had a smaller mortgage and lower interest paid — say $8,000 in mortgage interest, bringing her itemised total to roughly $20,500 — and the standard deduction exceeded that amount, itemising would provide no additional benefit. In that scenario, the mortgage interest deduction, while technically available, would be financially irrelevant to her — she'd simply take the standard deduction instead.
This illustrates why "is mortgage interest deductible" has a different practical answer depending on your specific loan size, other itemisable expenses, and the current standard deduction amount — always run your own numbers, ideally with a tax professional, rather than assuming the deduction automatically helps.