IRS Schedule A: Complete Guide to Itemized Deductions

Schedule A is the IRS form for itemized deductions; the detailed list of personal expenses that can reduce your taxable income beyond the standard deduction. From mortgage interest and charitable donations to state taxes and medical bills, Schedule A is where taxpayers who spend more than the standard deduction on deductible expenses can claim the difference. Since the Tax Cuts and Jobs Act nearly doubled the standard deduction in 2018, the number of itemizers has plummeted, but for those who qualify, the savings can be substantial.

History and Origin

Itemized deductions have been part of the U.S. tax code since the beginning of the modern income tax. The concept is straightforward: certain personal expenses are considered worthy of tax relief because they serve public policy goals. Charitable giving is encouraged, homeownership is subsidized through the mortgage interest deduction, and extraordinary medical costs receive relief.

For decades, a significant minority of taxpayers itemized. In the years before TCJA, roughly 30% of filers chose Schedule A over the standard deduction. This was especially common among homeowners in high-tax states, who could deduct substantial mortgage interest and state/local taxes.

The Tax Cuts and Jobs Act of 2017 transformed the landscape. By nearly doubling the standard deduction (from $6,350 to $12,000 for singles; $12,700 to $24,000 for married filing jointly) and simultaneously capping the state and local tax (SALT) deduction at $10,000, TCJA pushed the itemizing rate down to roughly 10% of filers. Millions of taxpayers who had itemized for decades suddenly found the standard deduction was a better deal.

The Pease limitation; a provision that reduced itemized deductions for high-income taxpayers; was eliminated by TCJA, providing some offset for wealthy filers who continued to itemize. This removal is also scheduled to expire after 2025 if TCJA sunsets.

Who Files It and When

You should file Schedule A when your total itemized deductions exceed your standard deduction. For the 2024 tax year, the standard deduction is:

• $14,600 for single filers and married filing separately
• $29,200 for married filing jointly
• $21,900 for head of household

Add $1,950 (single/HOH) or $1,550 (married) if you're 65 or older or blind.

Certain taxpayers must itemize regardless of amounts: married filing separately when your spouse itemizes (you cannot take the standard deduction if your spouse itemizes), nonresident aliens (in most cases), and dual-status aliens for the nonresident portion of the year.

Schedule A is filed with your Form 1040 by the regular April 15 deadline (or October 15 with an extension). There's no separate filing for Schedule A; it's always an attachment to the 1040.

Key Sections Explained

Medical and Dental Expenses (Lines 1-4)

You can deduct unreimbursed medical and dental expenses that exceed 7.5% of your adjusted gross income (AGI). This is a high threshold; for someone with $100,000 AGI, only expenses above $7,500 are deductible. Qualifying expenses include doctor visits, surgeries, prescriptions, dental work, vision care, health insurance premiums (if not pre-tax), and medically necessary home modifications.

Taxes You Paid (Lines 5-7); The SALT Deduction

This section covers state and local taxes, specifically:

• State and local income taxes OR state and local sales taxes (you choose one)
• Real estate (property) taxes
• Personal property taxes (vehicle registration fees based on value)

Under TCJA, the combined total was capped at $10,000 ($5,000 for married filing separately). Starting in 2025, the One Big Beautiful Bill Act raised the cap to $40,000 ($40,400 for 2026, indexed for inflation). However, the higher cap phases out for MAGI above $500,000, reverting to the $10,000 floor for high earners. Filers in high-tax states like New York, New Jersey, California, and Connecticut benefit significantly from the increased cap.

Interest You Paid (Lines 8-10)

Mortgage interest is the largest deduction here. You can deduct interest on up to $750,000 of mortgage debt ($375,000 married filing separately) for loans taken out after December 15, 2017. Loans from before that date are grandfathered at the old $1 million limit. Home equity loan interest is deductible only if the funds were used to buy, build, or substantially improve the home securing the loan. Investment interest (margin interest) is deductible up to net investment income.

Gifts to Charity (Lines 11-14)

Cash contributions are generally deductible up to 60% of AGI. Appreciated property (stocks held over a year) donated to public charities is deductible at fair market value up to 30% of AGI. You must have written acknowledgment for any single contribution of $250 or more. Non-cash contributions over $500 require Form 8283.

Casualty and Theft Losses (Line 15)

Under TCJA, casualty and theft loss deductions are limited to losses from federally declared disasters. The general personal casualty loss deduction was suspended from 2018-2025. Losses must exceed $100 per event plus 10% of AGI.

Other Itemized Deductions (Line 16)

Most miscellaneous itemized deductions were eliminated by TCJA, including the deduction for unreimbursed employee expenses, tax preparation fees, and investment advisory fees. Remaining deductions include gambling losses (to the extent of winnings), unrecovered pension basis, and certain other narrow categories.

Common Mistakes

• Itemizing when the standard deduction is higher; Some taxpayers itemize out of habit without checking whether the standard deduction now exceeds their itemized total. Always compare both.
• Exceeding the SALT cap without realizing it; Even with the higher $40,000 cap (2025+), high-income filers face a phaseout that reduces the cap back to $10,000 for MAGI above $500,000. Check your effective cap before assuming the full amount is deductible.
• Missing the AGI threshold for medical expenses; Many taxpayers claim the full amount of medical expenses without applying the 7.5% AGI floor. Only the excess over the threshold is deductible.
• Inadequate documentation for charitable donations; Cash donations of $250+ require a contemporaneous written acknowledgment from the charity. Without it, the deduction can be disallowed even if the donation was legitimate.
• Deducting home equity interest for non-qualifying uses; After TCJA, home equity loan interest is only deductible if the proceeds were used to improve the home. Using the money for a vacation or debt consolidation makes the interest non-deductible.
• Not considering "bunching" strategies; Alternating between itemizing and the standard deduction in consecutive years (by timing charitable donations and other deductions) can save significant taxes over time.

Recent Changes

• OBBBA SALT cap increase; The One Big Beautiful Bill Act (2025) raised the SALT cap from $10,000 to $40,000 ($40,400 for 2026, indexed for inflation). The higher cap phases out for MAGI above $500,000, reverting to the original $10,000 floor for high earners.
• Charitable deduction for non-itemizers expired; During 2020-2021, non-itemizers could deduct up to $300/$600 in charitable contributions above the line. This provision has expired, returning charitable deductions to Schedule A-only territory.
• More filers may benefit from itemizing — With the higher SALT cap under OBBBA, more taxpayers in high-tax states may find that itemizing beats the standard deduction again — especially homeowners with significant property taxes and state income taxes.
• Donor-advised funds growth — DAFs have surged in popularity as a bunching strategy. Taxpayers make large charitable contributions to a DAF in one year (itemizing that year), then distribute to charities over subsequent years while taking the standard deduction.
• State workarounds for SALT cap — Over 30 states have enacted pass-through entity tax (PTET) elections that allow business owners to deduct state taxes at the entity level. While less critical with the higher $40,000 cap, PTETs remain valuable for high-income filers subject to the phaseout.

This article is educational and does not constitute tax advice. Consult a qualified tax professional for guidance specific to your situation.