The best tax software has become so good at navigating the complex rules of federal income taxes that most tax filers can complete and submit their tax returns to the IRS without having to think about complicated worksheets for tax credits and deductions.

However, there's one tax term you'll need to figure out on your own in order to file your tax return online: adjusted gross income or AGI.

You'll need your AGI from last year's taxes to verify your identity online when you file in 2026, but this year's AGI is important, too. It will have an impact on the tax deductions and tax credits you can claim, as well as your tax bracket and tax rate.

Learn everything you need to know about AGI, how to find last year's info and what to do if you can't locate it. For more tax tips, learn when your taxes are due and how to track your tax refund.

What is adjusted gross income, or AGI?

Adjusted gross income includes all of the money you earned in a year minus certain adjustments. These adjustments are also called "above-the-line deductions," meaning you can use them to reduce your taxable income even if you take the standard deduction and don't itemize. AGI will also occasionally be called "taxable income."

Some of the above-the-line deductions that lower your AGI include:

• Retirement account contributions
• Student loan interest
• Health savings account contributions
• Alimony payments
• Educator expenses
• Eligible education expenses
• Moving expenses for members of the armed forces
• Some expenses for eligible artists
• One-half of the self-employment tax

Why do I need my AGI from last year to file taxes online in 2026?

The IRS uses your AGI from the previous year to verify your identity when you file taxes electronically. You can also use last year's five-digit Self-Select PIN, if you created one.

How can I find my AGI from last year?

The easiest way to find last year's AGI is to look at your 2024 tax return, specifically Line 11 of Form 1040. If you used online tax software to file last year, you can log into your account and look up your 2024 tax return there.

If you don't have last year's return and can't access it online, you can also find your AGI from your 2024 taxes with an online IRS account. Once you're logged into your IRS account, you can get a transcript of last year's taxes that shows your AGI. 

If you don't want to create an IRS account, you can also use Form 4506-T to request a 2024 tax transcript through the mail.

What should I use for last year's AGI if I didn't file a return?

If you didn't file taxes in 2025 or you're a first-time tax filer in 2026, simply put $0 for your AGI. 

If you are filing income taxes jointly and your partner didn't file last year, put $0 for the person who didn't file. Most online tax software will simply ask you if you filed and enter $0 automatically if you didn't.

What is MAGI, or modified adjusted gross income?

Your modified adjusted gross income, or MAGI, is another important number that can potentially impact your tax refund. Your MAGI is determined by adding back some deductions used to calculate AGI.

The most common of these deductions that are included to calculate MAGI are:

• Student loan interest
• Nontaxable Social Security benefits
• Tax-exempt interest
• Foreign-earned income
• One-half of the self-employment tax

For most taxpayers, AGI and MAGI will be very similar, but a difference can be critical, as some credits and deductions use thresholds based on MAGI. Your MAGI will determine if you qualify for a Roth IRA and if your retirement contributions are deductible. 

Several tax credits also use MAGI to determine eligibility or phase out, including the child tax credit, the education expenses credits and the premium tax credit for help with health insurance plans from the public marketplace.

For more tax tips, learn what to do if you didn't get your W-2 form this year and how the new crypto reporting rules work.