Above-the-line and below-the-line tax deductions are separated by a single number on your Form 1040: your Adjusted Gross Income. Above-the-line deductions come off your income before AGI is calculated, and you can claim them whether you take the standard deduction or itemize. Below-the-line deductions come after AGI and only help if your itemized total beats the standard deduction, which for 2026 is $16,100 for single filers and $32,200 for married couples filing jointly.1Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 That’s the whole framework. What follows is why the placement matters more than the label suggests.
Why the AGI Line Is the One That Matters
Gross income is everything that came in: wages, interest, dividends, business income, most other money. Subtract above-the-line adjustments and you get AGI, which sits on Form 1040 and acts as a gatekeeper for the rest of your return. Below-the-line deductions come next, either as the standard deduction or as itemized deductions on Schedule A, and they produce your taxable income.
The reason tax planners obsess over AGI is that dozens of other rules key off it. A lower AGI can enlarge credits, raise the share of medical bills you can deduct, keep you inside phase-out thresholds for education benefits, and even change your capital gains rate. Two people with the same gross income can owe very different amounts of tax depending on which side of the line their deductions fall.
Above-the-Line Deductions You Can Take Without Itemizing
These are reported on Schedule 1 and are sometimes called adjustments to income. Every dollar reduces AGI, and you keep them even if you later take the standard deduction.
Retirement and HSA Contributions
A traditional IRA contribution is deductible up to $7,500 for 2026, or $8,600 if you’re 50 or older, subject to income limits when you or your spouse is covered by a workplace retirement plan.2Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,5003Internal Revenue Service. Publication 590-A, Contributions to Individual Retirement Arrangements
Health Savings Accounts require a qualifying high-deductible health plan, but contributions go in tax-free, grow tax-free, and come out tax-free for medical spending. The 2026 limits are $4,400 for self-only coverage and $8,750 for family coverage.4Internal Revenue Service. Notice 26-05: HSA Inflation Adjusted Amounts for 2026
Self-Employment Adjustments
Self-employed filers can deduct the employer-equivalent half of their self-employment tax as an adjustment to income.5Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes) This lowers regular income tax, though it doesn’t reduce the self-employment tax itself. Health insurance premiums paid for yourself, a spouse, and dependents are also deductible above the line if you weren’t eligible for an employer-sponsored plan.
Student Loan Interest
Student loan interest is deductible up to $2,500 a year without itemizing, though the deduction phases out at higher incomes.6Internal Revenue Service. Topic No. 456, Student Loan Interest Deduction
Two Things That Look Like Above-the-Line Deductions But Aren’t Anymore
Alimony is deductible above the line only if the divorce or separation agreement was executed before 2019. Post-2018 agreements don’t qualify, and older ones modified to adopt the newer rules don’t either.7Internal Revenue Service. Topic No. 452, Alimony and Separate Maintenance Moving expenses have been limited since 2018 to active-duty Armed Forces members relocating on a permanent change of station; civilians can’t claim them.
Standard Deduction or Itemize: The Below-the-Line Choice
Once AGI is fixed, you pick between the standard deduction and itemizing on Schedule A.8Internal Revenue Service. About Schedule A (Form 1040), Itemized Deductions The standard deduction requires no receipts. For 2026:
- Single or married filing separately: $16,100
- Married filing jointly or surviving spouse: $32,200
- Head of household: $24,150
These figures reflect the One Big Beautiful Bill Act, signed in mid-2025, which made the higher standard deduction permanent. Taxpayers 65 or older can also claim a new senior deduction of $4,000 per qualifying individual for tax years 2025 through 2028, on top of the existing additional standard deduction for age and blindness.9Internal Revenue Service. 2026 Filing Season Updates and Resources for Seniors A married couple with both spouses 65 or older can add up to $8,000 in combined senior deductions under that provision alone.
Itemizing beats the standard deduction only when your qualifying expenses add up to more. Roughly 90% of taxpayers now take the standard deduction. If you own a home in a high-tax state and donate significantly, run the Schedule A numbers anyway.
What Still Counts If You Itemize
State and Local Taxes
The SALT deduction covers property taxes plus either state income taxes or state sales taxes, whichever is larger. Under the OBBB, the cap for 2026 is $40,000 ($20,000 for married filing separately), up from the $10,000 cap in place from 2018 through 2024. The cap phases down for modified AGI above $500,000, reduced by 30 cents for every dollar over the threshold, and taxpayers with modified AGI of $600,000 or more revert to the old $10,000 limit.
Mortgage Interest
Interest on debt used to buy or substantially improve a home is deductible on the first $750,000 of mortgage debt for loans taken out after December 15, 2017 ($375,000 if married filing separately). Older loans keep the previous $1 million limit.10Congress.gov. Reforms to the Mortgage Interest Deduction with Revenue Estimates The OBBB made the $750,000 threshold permanent.
Medical and Dental Expenses
Unreimbursed medical and dental expenses are deductible only to the extent they exceed 7.5% of AGI.11Internal Revenue Service. Publication 502, Medical and Dental Expenses At an AGI of $80,000, that means the first $6,000 of medical bills produce no deduction at all. This one tends to matter in years with major surgery, long hospital stays, or expensive dental work.
Charitable Contributions
Cash gifts to public charities are deductible up to 60% of AGI.12Internal Revenue Service. Publication 526, Charitable Contributions Appreciated property, gifts to private foundations, and certain other donations face 20% or 30% limits. Excess amounts carry forward for up to five years. Keep receipts, and get a written acknowledgment from the charity for any single gift of $250 or more.
Deductions That No Longer Qualify
Before 2018, itemizers could deduct tax preparation fees, unreimbursed employee business expenses, investment advisory fees, and similar costs that together exceeded 2% of AGI. The Tax Cuts and Jobs Act suspended these miscellaneous itemized deductions, and the OBBB made the suspension permanent.
The educator expense deduction is also changing. Through 2025, teachers could deduct up to $300 of unreimbursed classroom costs ($600 for two married educators) as an above-the-line adjustment.13Internal Revenue Service. Topic No. 458, Educator Expense Deduction Starting in 2026, the OBBB removes the dollar cap but moves the deduction to Schedule A. Only educators who itemize will benefit.
Why Above-the-Line Usually Beats Below-the-Line, Dollar for Dollar
A dollar of above-the-line deduction and a dollar of itemized deduction both reduce taxable income by a dollar. But because AGI drives so many other pieces of the return, the above-the-line dollar often keeps working after the itemized dollar has stopped.
Credits That Phase Out
The Child Tax Credit for 2026 is worth up to $2,200 per qualifying child under 17, up to $1,700 of that refundable. It’s fully available at AGI up to $200,000 (single) and $400,000 (married filing jointly), then phases down.14Internal Revenue Service. Child Tax Credit The Earned Income Tax Credit uses both earned income and AGI to determine eligibility and size, with a maximum for 2026 of $8,231 for a family with three or more children.1Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 Above-the-line deductions can move you across these thresholds. Itemized deductions can’t.
Investment Surcharges and Capital Gains
The 3.8% Net Investment Income Tax applies once modified AGI exceeds $200,000 (single) or $250,000 (married filing jointly), on the lesser of net investment income or the amount over the threshold.15Internal Revenue Service. Topic No. 559, Net Investment Income Tax A well-timed IRA or HSA contribution can drop you below the line and cancel the surcharge.
Long-term capital gains rates depend on taxable income, and taxable income flows from AGI. For 2026, single filers pay 0% on long-term gains while taxable income stays at or below $49,450; the joint threshold is $98,900.16Internal Revenue Service. Topic No. 409, Capital Gains and Losses Above-the-line deductions that shrink AGI can keep gains inside the 0% bracket.
The Medical Floor Interaction
The 7.5% medical floor is itself a function of AGI. Reduce AGI by $10,000 through IRA and HSA contributions, and the floor drops by $750, so more of your medical bills clear it and become deductible below the line. The two sides of the line aren’t sealed off from each other.
Documentation for Each Side
Above-the-line deductions largely document themselves. Your IRA custodian issues Form 5498, your HSA administrator issues Form 5498-SA, and your student loan servicer issues Form 1098-E. Keep the forms with your return.
Itemized deductions require more effort. Save property tax bills, state tax returns, the Form 1098 mortgage interest statement, medical receipts, and written acknowledgments for charitable gifts of $250 or more. Keep supporting records for at least three years from the date you filed.17Internal Revenue Service. How Long Should I Keep Records