Adjusted gross income, or AGI, is your total income for the year minus a specific list of deductions that federal law lets you take before you choose between the standard deduction and itemizing. It sits on line 11 of Form 1040, and it drives almost every phase-out, credit limit, and deduction floor in the tax code.1Internal Revenue Service. Definition of Adjusted Gross Income Getting the number right is the difference between qualifying for benefits worth thousands of dollars and missing them.
What Counts as Income
AGI starts with gross income, which federal law defines as all income from whatever source unless a specific rule excludes it.2Office of the Law Revision Counsel. 26 USC 61 – Gross Income Defined The statute names fourteen categories, including wages, business income, gains from property, interest, rents, royalties, dividends, annuities, and pensions, and then adds “but not limited to” so nothing slips through on a technicality.
In practice, most filers pull the numbers straight off information returns. Wages come from the W-2. Interest is reported on Form 1099-INT, dividends on Form 1099-DIV.3Internal Revenue Service. About Form 1099-INT, Interest Income Capital gains from selling stocks, bonds, or property get worked out on Schedule D.4Internal Revenue Service. Instructions for Schedule D (Form 1040) Retirement distributions show up on Form 1099-R, gambling winnings on Form W-2G, and unemployment compensation and the taxable share of Social Security also count.
Self-employed filers report the net profit from Schedule C, meaning revenue after ordinary business expenses.5Internal Revenue Service. About Schedule C (Form 1040), Profit or Loss from Business (Sole Proprietorship) That net figure, not gross receipts, is what feeds into gross income.
Some money that hits your account never makes it into AGI. Tax-exempt interest, most commonly from municipal bonds, gets reported on line 2a of Form 1040 but is not added in.6Internal Revenue Service. Instructions for Schedule B (Form 1040) Life insurance death benefits, gifts, and most inheritances are also excluded. The default rule is that income is taxable unless a specific Code section says otherwise, so if you’re unsure, assume it counts until you can point to the exclusion.
The Adjustments That Get You to AGI
Once gross income is tallied, you subtract a defined set of deductions listed in 26 U.S.C. §62.7Office of the Law Revision Counsel. 26 USC 62 – Adjusted Gross Income Defined These are called “above-the-line” adjustments because they come before the standard-versus-itemized choice, and you get them either way. Most are reported on Schedule 1 of Form 1040. The common ones:
- Half of self-employment tax. If you work for yourself, you pay both the employer and employee share of Social Security and Medicare. You deduct the employer-equivalent half as an adjustment, which can knock several thousand dollars off AGI at typical self-employment income levels.8Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes)
- Self-employed health insurance premiums, if you aren’t eligible for a subsidized plan through a spouse’s employer and the plan is established under your business. The deduction cannot exceed net business profit.9Internal Revenue Service. Instructions for Form 7206
- HSA contributions. For 2026, you can put in up to $4,400 with self-only coverage or $8,750 with family coverage, plus $1,000 more if you’re 55 or older. Reported on Form 8889.10Internal Revenue Service. Instructions for Form 8889
- Traditional IRA contributions, up to the 2026 limit of $7,500 per person, subject to income-based phase-outs if you or your spouse are covered by a workplace retirement plan.11Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500
- Student loan interest, up to $2,500. If you paid $600 or more, your servicer sends Form 1098-E.12Internal Revenue Service. Topic No. 456, Student Loan Interest Deduction
- Educator expenses, up to $300 in unreimbursed classroom supplies and professional development for K–12 teachers, counselors, and principals who work at least 900 hours a year.13Internal Revenue Service. Topic No. 458, Educator Expense Deduction
- Military moving expenses tied to active-duty orders, calculated on Form 3903.14Internal Revenue Service. Topic No. 455, Moving Expenses for Members of the Armed Forces and the Intelligence Community
- Alimony paid under a divorce or separation agreement finalized before 2019 and not modified since. Agreements executed after December 31, 2018 carry no deduction for the payer and no taxable income for the recipient.15Internal Revenue Service. Topic No. 452, Alimony and Separate Maintenance
The total on Schedule 1, Part II, subtracted from gross income, is your AGI on line 11. Missing an adjustment doesn’t just mean paying more tax on the return in front of you; it can also push you over an income threshold and cost you a credit worth more than the deduction itself.
Why the Number Matters
AGI runs the phase-out machinery. If you itemize, medical and dental expenses only count above 7.5% of AGI, so at $80,000 of AGI you’d need more than $6,000 in qualifying costs before the first dollar becomes deductible.16Internal Revenue Service. Topic No. 502, Medical and Dental Expenses Charitable contributions are capped as a share of AGI too: cash gifts to most public charities up to 60%, gifts to certain private foundations and veterans’ organizations up to 30%, with excess amounts generally carried forward up to five years.17Internal Revenue Service. Charitable Contribution Deductions
Credits are keyed to AGI as well. The Child Tax Credit begins phasing out at $200,000 for single filers and $400,000 for married couples filing jointly.18Internal Revenue Service. Child Tax Credit The Earned Income Tax Credit phases out at much lower thresholds that vary by filing status and number of children. And the Net Investment Income Tax adds 3.8% on the lesser of net investment income or the amount by which modified AGI exceeds $250,000 for joint filers, $200,000 for single filers, or $125,000 for married filing separately. Those thresholds are not indexed for inflation.19Internal Revenue Service. Net Investment Income Tax
For context on the choice between standard and itemized: the 2026 standard deduction is $16,100 for single filers, $32,200 for married filing jointly, and $24,150 for heads of household.20Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 Most filers take the standard deduction, but AGI-based limits still shape what’s left of itemized deductions for those who do itemize.
Modified AGI Is a Separate Number
Several important tax benefits don’t use plain AGI. They use modified adjusted gross income, or MAGI, which starts with AGI and adds back specific items you already deducted or excluded. There is no single MAGI formula. The add-backs depend on which benefit you’re testing eligibility for.21Internal Revenue Service. Modified Adjusted Gross Income
Common add-backs include foreign earned income excluded on Form 2555, tax-exempt interest, the student loan interest deduction, the IRA deduction, and nontaxable Social Security benefits. When the IRS decides whether your Social Security benefits are taxable, it adds tax-exempt interest back into AGI. When it checks Premium Tax Credit eligibility, it adds both tax-exempt interest and nontaxable Social Security. MAGI is the gatekeeper for education credits, Roth IRA contribution eligibility, the traditional IRA deduction phase-out, Coverdell ESA contributions, the Premium Tax Credit, and the adoption credit, among others. If you’ve been told you make too much for a Roth IRA, MAGI is what crossed the line.
Finding Last Year’s AGI
You need last year’s AGI whenever you e-file, because the IRS uses it as an identity check before accepting the return.22Internal Revenue Service. Validating Your Electronically Filed Tax Return If you don’t have a copy of last year’s return, you have a few options: check your IRS Online Account under the Tax Records tab, request a transcript by mail or by calling 800-908-9946, or open the tax software you used last year. A paid preparer can also retrieve it.
If you have an Identity Protection PIN from the IRS, that substitutes for prior-year AGI during validation. First-time filers enter zero.
The Cost of Getting It Wrong
A return that understates tax by a substantial amount can draw a 20% accuracy-related penalty on the underpaid portion, applied to negligence, disregard of IRS rules, and substantial understatements of income.23Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty on Underpayments Willful evasion is a separate matter, punishable by a fine of up to $100,000 (or $500,000 for a corporation) and up to five years in federal prison.24Office of the Law Revision Counsel. 26 USC 7201 – Attempt to Evade or Defeat Tax Forgetting a 1099 you never received is not the same as concealing freelance income, and the IRS treats them very differently, but both start with the same line 11 you’re trying to get right.