Line 15 on your tax return is your taxable income, the amount of your earnings actually subject to federal income tax after deductions come out. It sits at the bottom of page one of IRS Form 1040, on the last line of the income section, labeled “This is your taxable income.” The number comes from a simple subtraction: your adjusted gross income on Line 11 minus your deductions on Line 14.1Internal Revenue Service. Form 1040 – 2025 U.S. Individual Income Tax Return
Where to Look on the Form
Line 15 is on page one, not page two. Scroll or flip to the very bottom of the first page and it’s the last entry before the “Tax and Credits” section begins on page two at Line 16.1Internal Revenue Service. Form 1040 – 2025 U.S. Individual Income Tax Return
If you filed electronically, you may not have a paper form to flip through. Most tax software lets you view or download a PDF of your completed Form 1040 after filing. TurboTax, for example, keeps this behind “View Tax Summary” and then “Preview my 1040.” Other programs have similar options under account or return history.
If you can’t get to your software copy, you can request a tax return transcript from the IRS. The transcript reproduces the key line items from your filed return, taxable income included.2Internal Revenue Service. Transcript Types for Individuals and Ways to Order Them
How the Number Is Calculated
The math is straightforward. Start with adjusted gross income on Line 11, then subtract Line 14.1Internal Revenue Service. Form 1040 – 2025 U.S. Individual Income Tax Return AGI is all your income (wages, investment gains, business profit, retirement distributions) minus a set of “above the line” adjustments like student loan interest and certain retirement contributions.3Internal Revenue Service. Definition of Adjusted Gross Income
Line 14 combines up to three things: your standard or itemized deduction, plus the qualified business income deduction if you qualify. For the 2026 tax year, the standard deduction is $16,100 for single filers or married filing separately, $32,200 for married filing jointly, and $24,150 for head of household.4Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
If you freelance, run a business, or earn income through a pass-through entity, you may also qualify for the qualified business income deduction, which lets eligible taxpayers deduct up to 20% of qualified business income subject to income limits and other restrictions.5Office of the Law Revision Counsel. 26 USC 199A – Qualified Business Income That amount rolls into Line 14 alongside your standard or itemized deduction before the final subtraction.
A quick example. A single filer with $31,100 in AGI who takes the $16,100 standard deduction would show exactly $15,000 on Line 15.
When Line 15 Is Zero
If your deductions equal or exceed your AGI, the Form 1040 instructions tell you to enter zero. Taxable income cannot be negative. This happens more often than people expect, particularly for retirees with modest Social Security income and low-wage workers eligible for large deductions. A zero on Line 15 means no federal income tax on that year’s earnings, though you may still owe payroll taxes on wages or self-employment tax on business income.1Internal Revenue Service. Form 1040 – 2025 U.S. Individual Income Tax Return
Line 15 vs. Line 11: Which Number Do Forms Actually Want?
This is where people get tripped up. Many applications ask for “income from your tax return,” and they usually mean adjusted gross income on Line 11, not taxable income on Line 15. These are different numbers, and mixing them up can delay applications or produce incorrect eligibility results.
AGI is your total income minus above-the-line adjustments, calculated before deductions. Taxable income is AGI minus deductions. AGI is always equal to or higher than taxable income.3Internal Revenue Service. Definition of Adjusted Gross Income
A few concrete examples of who wants which number:
- Federal student loan servicers use AGI to set monthly payments under income-driven repayment plans. Your payment is based on a percentage of the gap between AGI and a poverty-line threshold, so itemized deductions that lower your taxable income will not reduce your student loan bill.6Federal Student Aid. Discretionary Income
- Health insurance subsidies through the ACA marketplace use modified adjusted gross income, which is usually identical to AGI for most filers.
- Mortgage lenders tend to look at multiple lines on your return depending on your income sources rather than a single line. Self-employed borrowers should expect scrutiny of business income schedules beyond Line 15.
If a form asks for income from your most recent return without specifying a line number, check the instructions to confirm whether it means AGI (Line 11) or taxable income (Line 15). The wrong number can delay processing or skew a benefit calculation.
Line 15 Feeds Line 16, Not Your Final Tax Bill
Taxable income and the actual tax you owe are not the same thing. Line 15 is what the IRS runs through the tax brackets to produce the tax figure on Line 16. From there, credits reduce what you owe. Nonrefundable credits can bring your tax to zero but no lower. Refundable credits like the earned income tax credit can drop the balance below zero and generate a refund even if you owed nothing to begin with. So a large number on Line 15 does not mean you will pay that much, and a small number does not mean you will pay nothing.
Why an Error on Line 15 Matters
If you understate taxable income by a large enough margin, the IRS can impose a 20% accuracy-related penalty on the underpaid tax. An understatement is “substantial” when it exceeds the greater of $5,000 or 10% of the tax that should have been shown on your return.7Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty on Underpayments If you claimed the qualified business income deduction, the threshold drops to 5%, making the penalty easier to trigger.
The penalty applies only to the underpaid portion. An error that produced $2,000 in additional tax would carry a $400 penalty on top of the tax owed, plus interest running from the original due date. Reasonable cause and good faith can defeat the penalty, but “I didn’t understand the form” rarely qualifies on its own. Records that back up every deduction you claim are the most reliable defense.
There’s a second reason to get Line 15 right: state returns. Most states with an income tax start their calculation from federal AGI, but a handful start from federal taxable income. In those states, an error on Line 15 flows straight through to what you owe the state. Even where the state starts from AGI, the IRS and state revenue agencies share data and flag mismatches between the two returns.