Deduction for mortgage interest
Interest paid on home loans reduces taxable income for itemisers.
JCT line: "Deduction for mortgage interest on owner-occupied residences".
JCT Table 3 puts 78% of the deduction on returns over $200,000. Returns under $100,000 account for about 3%, a consequence of the 2017 standard deduction increase removing most filers from itemising.
Of $52.6B in total benefit. JCT, Estimates of Federal Tax Expenditures for Fiscal Years 2025-2029 (JCX-45-25), Table 3.
Of 160,602,107 returns filed for tax year 2023. IRS, Statistics of Income, Individual Income Tax Returns, Table 2.1 (TY2023).
Structural reading
The most instructive entry on this list, because it is the one that shrank. For decades it was among the largest tax expenditures and was regarded as politically untouchable. The 2017 act cut its cost by roughly two thirds, not by repealing it, which would have triggered organised opposition, but by raising the standard deduction so that most filers no longer itemised. The lesson is structural rather than partisan: concentrated benefits are rarely defeated head-on, and the reforms that succeed tend to work by changing the surrounding architecture rather than by attacking the provision directly.
Who gets it
The channels the benefit actually flows through, described by asset position, entity form and form of return. Never by named individuals.
Cost split by the concentration score. That score is a judgement rather than a published figure, so treat this as the scale of the split, not an audited allocation.
- Itemising households with large mortgages
Benefit scales with both loan size and marginal rate, so it is largest for expensive homes financed by higher-bracket borrowers.
- Mortgage originators and the housing finance chain
The deduction subsidises debt-financed rather than equity-financed ownership, structurally favouring larger loans.
- Existing owners via capitalisation into prices
Research indicates a substantial share of the subsidy capitalises into house prices, benefiting owners at the time of enactment rather than subsequent buyers.
Who pays
Renters, non-itemising owners, and taxpayers generally.
Sector aggregate.
This transfer follows a general pattern, asymmetric organisation, sustained expert attention, and scheduled expiry dates.
How rent-seeking works →Legislative history and accountability
Enacting statutes, major amendments, recorded votes with party breakdown, and live reform proposals.
Enabling legislation
- Revenue Act of 1913Oct 3, 1913
All interest was deductible from the outset of the modern income tax, with no specific intent to subsidise homeownership.
No separate recorded vote on this provision, it passed by voice, predates recorded electronic voting, or moved inside a larger package voted on as a whole.
Major amendment
- Tax Reform Act of 1986P.L. 99-514Oct 22, 1986
Eliminated the deduction for personal interest generally but carved out mortgage interest, converting an incidental feature into a deliberate housing subsidy.
BipartisanEnacted by a Republican president and a divided Congress with broad support from both parties, the most bipartisan major tax reform of the modern era. No separate roll call on this provision is recorded here. unverified
- Tax Cuts and Jobs Act of 2017P.L. 115-97Dec 22, 2017
Capped qualifying principal at $750,000 and, by nearly doubling the standard deduction, removed most filers from itemising, cutting the provision's cost by roughly two-thirds.
houseDec 20, 2017· Agreed to, 224-201Who voted which way: full roll callDemocratic0 yea189 nay0% yeaRepublican224 yea12 nay95% yeasenateDec 20, 2017· Agreed to, 51-48Who voted which way: full roll callDemocratic0 yea46 nay0% yeaRepublican51 yea0 nay100% yeaIndependent / other0 yea2 nay0% yea
Lobbying around this provision
This is not campaign money, and it is not attributable to the votes above. Lobbying disclosures record what organisations spent engaging policymakers across an entire issue area over a quarter. They are not broken out by party, by member, or by bill, and no part of this figure can be traced to any vote on this page. It is shown as an indicator of how organised the interest around this provision is, nothing more.
Demonstrating an actual relationship between money and votes would require campaign contribution records matched to each member of the roll call. That is a different dataset and is not yet built here.
Senate LDA filings, search disclosures by filer and issueSources and data freshness
Published within the last year. Figures marked unverified are seed estimates that have not been reconciled line-by-line against the primary source document. See the methodology for how each score is constructed.
Cite this figure
JCT, Estimates of Federal Tax Expenditures for Fiscal Years 2025-2029 (JCX-45-25), Table 1, published Dec 3, 2025. FY2025 estimate for "Deduction for mortgage interest": $45,500,000,000. https://www.jct.gov/publications/2025/jcx-45-25/ Via RentSeek, https://rentseek.bothand.tech/transfer/mortgage-interest-deduction
The primary document is cited first on purpose. Send your reader to the source table rather than to this site, which is a finding aid and not the authority for any figure on it.