No, your state adjusted gross income is usually not the same as your federal AGI. Most states that tax income start with the federal AGI from Line 11 of your Form 1040, then require a set of additions and subtractions that reflect their own policy choices. The gap can be a few dollars or tens of thousands, depending on the type of income you have and the state you file in.
Here is what drives the difference, and where to look on your state return to find it.
How States Connect to Your Federal Return
Roughly 30 states and the District of Columbia use federal AGI as the opening figure on their income tax returns. About five states start from federal taxable income instead, which is the number after your standard or itemized deduction. A few states ignore the federal return altogether and calculate income from scratch under their own definitions. So the phrase “state AGI” means something slightly different depending on where you file.
States that borrow from the federal tax code do so through what tax professionals call conformity, and it comes in two forms.
Rolling Conformity
In a rolling conformity state, the state tax code automatically incorporates changes to the federal Internal Revenue Code as they happen. When Congress passes a new deduction or modifies an existing one, that change flows into the state’s calculations without any state legislative action. About half the states with an income tax operate this way.
Static Conformity
Static conformity states adopt the Internal Revenue Code as it existed on a specific date. Any federal change made after that date has no effect on the state’s tax base until the state legislature passes an update bill. Your federal return might reflect a deduction that your state doesn’t yet recognize, or the reverse.
This distinction matters in 2026 because the One, Big, Beautiful Bill Act made permanent several provisions from the 2017 Tax Cuts and Jobs Act and restored 100% bonus depreciation. Rolling conformity states absorbed those changes automatically. Static conformity states pegged to an earlier date may not recognize them yet, which can create meaningful differences between federal and state returns for the same tax year.
Additions That Push State AGI Above Federal
Even in high-conformity states, the return will usually ask you to add certain amounts back to federal AGI. These additions reflect deliberate policy choices, and they make your state taxable income larger than the federal baseline.
Out-of-State Municipal Bond Interest
Interest earned on bonds issued by a state or local government is excluded from federal gross income under the tax code.1Office of the Law Revision Counsel. 26 USC 103 – Interest on State and Local Bonds Because the interest never enters federal AGI, most states honor the exclusion for bonds they issued themselves but require you to add back interest earned on bonds issued by other states. If you hold a diversified municipal bond fund, a portion of that interest is likely taxable on your state return even though none of it appeared federally.
Depreciation Differences
Federal bonus depreciation lets businesses deduct a large percentage of an asset’s cost in the year it’s placed in service. Several states either reject bonus depreciation or allow it at a reduced rate, requiring you to add back the difference and spread the deduction over a longer recovery period. The state-level depreciation is typically calculated under a slower method, so the add-back raises state income in the early years and produces a subtraction later as the state deduction catches up.
State and Local Tax Deduction Add-Back
If you itemize on your federal return and deduct state or local income taxes on Schedule A, some states require you to add that deduction back for state purposes. Allowing a state tax deduction against the state’s own tax base would let the tax partially subsidize itself, so the add-back closes the loop. This one often surprises filers who assume federal itemized deductions carry straight through to the state.
Qualified Business Income Deduction
The Section 199A qualified business income deduction lets eligible business owners deduct up to 20% of qualified business income on their federal returns.2Internal Revenue Service. Qualified Business Income Deduction A number of states do not allow this deduction at the state level and require you to add the full amount back when computing state income. For a small business owner, this single adjustment can raise state AGI by tens of thousands of dollars.
Subtractions That Pull State AGI Below Federal
Subtractions work in the opposite direction, reducing state income below your federal AGI. States use these to pursue policy goals like retaining retirees, supporting military families, or encouraging education savings.
Retirement Income
This is where some of the largest gaps show up. Several states partially or fully exclude Social Security benefits, pension distributions, or other qualified retirement income from state taxation. The exclusions vary: some apply only after a certain age, some cap the dollar amount, and some limit the benefit to specific types of retirement plans. A pension that’s fully taxable federally may be partly or entirely subtracted at the state level.
State Tax Refunds
When you receive a refund of state or local income taxes, the IRS may require you to include it in federal gross income if you itemized in the prior year and benefited from deducting those taxes.3Internal Revenue Service. Taxable Refunds, Credits or Offsets of State or Local Income Taxes That refund inflates federal AGI. Most states allow a subtraction for the same amount, because taxing the return of their own tax dollars doesn’t make policy sense.
Military Pay
Federal law prevents a duty station state from taxing a servicemember’s military income when they are stationed away from home. Beyond that federal floor, many states offer a partial or complete subtraction for active-duty military pay earned by their own residents. The pay still appears in federal AGI, so the state subtraction creates a direct gap between the two figures.
529 Plan Contributions
Contributions to 529 education savings plans receive no federal income tax deduction.4Internal Revenue Service. 529 Plans: Questions and Answers Over 30 states allow a deduction or credit for contributions to the state’s own plan, and some extend the benefit to contributions to any state’s plan. Because the deduction lives only at the state level, it creates a subtraction from federal AGI that has no federal counterpart.
When Your State Doesn’t Use Federal AGI at All
A few states build their income tax from the ground up, defining their own version of gross income, their own allowable deductions, and their own exemptions. Residents of these states fill out a return that looks nothing like a modified 1040. You can’t copy numbers straight from the federal form; you have to reclassify income and deductions under the state’s separate framework.
About five states take a middle path and start from federal taxable income rather than federal AGI. Because federal taxable income already reflects the standard or itemized deduction, some of the add-backs an AGI-starting state might require are already baked in. Moving between an AGI-starting state and a taxable-income-starting state mid-year makes the two part-year returns harder to reconcile.
Eight states impose no individual income tax at all as of 2026, and one additional state taxes only capital gains from investment sales. If you live in one of those states, there is no state AGI to calculate. Federal AGI is the only income figure that matters for tax purposes, unless you earn income in another state through remote work, a rental property, or a business, in which case that state will typically ask for a nonresident return that starts from your federal AGI and applies its own rules.
Why the Difference Matters
The gap between federal and state AGI isn’t just an accounting curiosity. It changes the amount of tax you owe, the credits you qualify for, and the estimated payments you need to make during the year.
State credits and deductions often phase out based on state AGI, not federal. You might qualify for a federal credit because your federal AGI falls below the threshold and still lose a state credit because a required add-back pushed your state AGI above the state’s cutoff. The reverse happens too: a generous state subtraction for retirement income can drop your state AGI low enough to qualify for state benefits your federal income would have disqualified you from.
Estimated tax payments are where miscalculations tend to bite hardest. If you base your quarterly state payments on federal AGI without accounting for state additions, you’ll underpay. States charge interest on underpayments, typically in the range of 7% to 11% annually, and some add a flat penalty on top. A safe harbor approach, paying at least 100% of your prior-year state tax liability or 90% of the current year’s, can protect you from penalties, but only if you calculate the safe harbor amount using the correct state figure.
The most reliable way to identify every addition and subtraction that applies to you is the modifications schedule your state includes with its return, usually a dedicated form or worksheet. Working through that schedule line by line is what turns your federal AGI into the state AGI you actually owe tax on.