Modified adjusted gross income (MAGI)

Your adjusted gross income (AGI) is the total on line 11a of the 2025 Form 1040. Each rule that uses MAGI makes its own changes to AGI, so you can have several MAGIs in one year. If none of a rule’s changes apply to you, your MAGI for that rule equals your AGI.

For the 3.8% net investment income tax, MAGI is AGI plus any foreign earned income you excluded. The tax can apply above $200,000 of that MAGI, $250,000 on a joint return, or $125,000 filing separately. None of these amounts rises with inflation.

The cap on the state and local tax (SALT) deduction uses the same MAGI. It also adds back income excluded by residents of Puerto Rico and certain US possessions. For 2026, the cap starts to shrink above $505,000 of MAGI, or $252,500 filing separately.

For Roth IRA contributions, MAGI adds back items such as a traditional IRA deduction and excluded foreign earned income. In 2026, a single filer’s Roth IRA contribution limit phases out as this MAGI rises from $153,000 to $168,000. On a joint return, the range is $242,000 to $252,000.

The usual mistake is to use one MAGI for every rule. Roth conversion income is left out when testing Roth contributions. It still raises your MAGI for the 3.8% tax. A large bonus or RSU vest raises every version, because each one starts from AGI.