Form 1040

11a — Adjusted Gross Income Updated for tax year 2025

What this line means

Your total income minus a set of specific “above-the-line” deductions — things like student loan interest, HSA contributions, and IRA contributions. AGI is not your final taxable income, but it controls nearly everything that comes after: eligibility for credits, the size of deduction add-ons, and even your Medicare premiums.

Does this apply to you?

  • Every filer completes this line — it is calculated automatically from lines 9 and 10
  • The number matters most if you are near an income threshold for a Roth IRA, ACA subsidy, or student loan deduction phase-out

Easy to overlook

AGI determines Roth IRA eligibility The ability to contribute to a Roth IRA starts phasing out at $150,000 AGI (single) and $236,000 (married filing jointly) in 2025. Many filers do not realize that reducing AGI — by maximizing an HSA or traditional IRA — can restore Roth eligibility they thought they had lost. 1 [SOURCE: IRS Publication 590-A]

IRMAA Medicare surcharges If AGI exceeds $106,000 (single) or $212,000 (MFJ), Medicare Part B and Part D premiums increase substantially. The surcharge uses your return from two years prior, so a one-time income spike — a home sale, a Roth conversion — can raise your Medicare bill two years later. 2 [SOURCE: CMS IRMAA lookup tables]

Watch out for this

Not taking all available above-the-line deductions before calculating AGI. Student loan interest, HSA contributions, self-employed health insurance, and traditional IRA contributions all reduce AGI directly. Filers who miss these do not just lose the deduction — they also inflate the AGI that gates access to other benefits.

  • Line 10 — Form 1040 — Adjustments to income; these reduce line 9 to get to line 11a
  • Line 12e — Form 1040 — Standard or itemized deduction; applied after AGI is calculated
  • Line 15 — Form 1040 — Taxable income; the final number that determines your actual tax

Footnotes

  1. IRS Publication 590-A, Contributions to Individual Retirement Arrangements (IRAs). https://www.irs.gov/pub/irs-pdf/p590a.pdf ↩

  2. Centers for Medicare & Medicaid Services, Income-Related Monthly Adjustment Amount (IRMAA). https://www.cms.gov/medicare/costs/medicare-costs-glance ↩

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