Updated October 17, 2026. Quick answer: Line 14 is the total of your deductions: the form says to add lines 12e, 13a, and 13b. Line 15 is your taxable income, found by subtracting line 14 from line 11b, and entering zero if the result is zero or less. Neither line needs a form of its own; both are arithmetic on lines you have already filled in.
Business use of your home (Form 8829), the saver’s credit (Form 8880), clean vehicle credits (Form 8936) and amended returns (Form 1040-X), read line by line: Form 1040-X lines 1 to 3 and Form 1040-X lines 4a to 5.
IRS worksheets from the 2025 Form 1040 instructions, read line by line: Standard Deduction Worksheet for Dependents, Student Loan Interest Deduction Worksheet and Form 1040 worksheets.
What lines 14 and 15 ask for
The form’s caption for line 14 reads “Add lines 12e, 13a, and 13b”. The caption for line 15 reads “Subtract line 14 from line 11b. If zero or less, enter -0-. This is your taxable income”. The form’s own wording above is the plain guide to both lines. The rest of the return is mapped in Form 1040 line by line.
Line 14: total deductions
Line 14 collects three earlier lines. Line 12e is the standard deduction or itemized deductions, explained on line 12. Line 13a is the qualified business income deduction and line 13b is the additional deductions from Schedule 1-A, both explained on line 13. Each of those lines is filled in first and then the three are added together on line 14.
A labelled illustration, not an IRS example, of the form-defined arithmetic: if line 12e were $20,000 and line 13a were $5,000 and line 13b were $1,000 then line 14 would be $20,000 plus $5,000 plus $1,000 for a total of $26,000. The figures are made up to show the addition only and are not a deduction amount for any taxpayer.
Line 15: taxable income
Line 15 starts from line 11b. The caption for line 11b reads “Amount from line 11a (adjusted gross income)”, so line 11b repeats your adjusted gross income from page 1. That figure is covered on the lines 9, 10 and 11 page. Line 15 subtracts line 14 from it. The form’s caption also says what to do if the result is not above zero: “If zero or less, enter -0-.”
Continuing the same illustration, not an IRS example, computed from made up numbers: if line 11b were $80,000 and line 14 were $26,000 then line 15 would be computed as $80,000 minus $26,000 which is $54,000. If line 14 were larger than line 11b, the subtraction would give zero or less, and the form says to enter -0-.
Where the number comes from
Everything on these two lines comes from other lines of the same form. Line 14 draws on lines 12e, 13a and 13b. Line 15 draws on line 11b and line 14. There is no outside document to copy from. Because the arithmetic is simple, errors usually come from the lines above: a wrong adjusted gross income on line 11b, or a deduction entered on the wrong line.
The instructions’ final-check list says to “Check your math, especially for the child tax credit, earned income credit (EIC), taxable social security benefits, total income, itemized deductions or standard deduction, taxable income, total tax”. Taxable income and the deductions are on that list.
Where it goes next
Line 15 is the amount your tax is figured on. The instructions for line 16 say “If your taxable income is less than $100,000, you must use the Tax Table, later in these instructions, to figure your tax.” and “If your taxable income is $100,000 or more, use the Tax Computation Worksheet right after the Tax Table.” The worksheets also start from line 15: the Qualified Dividends and Capital Gain Tax Worksheet begins “Enter the amount from Form 1040 or 1040-SR, line 15.” See line 16 for how the tax is figured and the qualified dividends worksheet page for that worksheet.
A special case: the Foreign Earned Income Tax Worksheet
One worksheet in the instructions carries its own instruction about line 15: “If Form 1040 or 1040-SR, line 15, is zero, don’t complete this worksheet.” That worksheet is for filers who claimed the foreign earned income exclusion, housing exclusion or housing deduction on Form 2555, and it does not apply to most returns.
Edition and line numbers
This page reads the 2025 Form 1040 and its 2025 instructions, the current files irs.gov served on 2026-10-17. They are the forms for the tax year 2025 return, filed in 2026. The instructions say “The lines on Forms 1040 and 1040-SR are the same.” so everything here applies to Form 1040 and to Form 1040-SR alike. The captions for lines 14 and 15 are as quoted above. Check the tax year printed on the form you are filling in and use the line numbers on that year’s form, because a different year’s form can number or word its lines differently.
Common mistakes
- Leaving a deduction out of line 14. The form’s caption reads “Add lines 12e, 13a, and 13b”, so all three lines count.
- Entering a negative number on line 15. The form says “If zero or less, enter -0-.”
- Starting from the wrong line. The caption says to subtract line 14 from “line 11b”, the adjusted gross income repeated on page 2, not from total income on line 9.
Related: Qualified dividends worksheet, 2025 tax brackets, Form 1040, and Standard deduction 2025.
Sources
- Instructions for Form 1040 and Form 1040-SR (2025): https://www.irs.gov/pub/irs-pdf/i1040gi.pdf
- Form 1040, U.S. Individual Income Tax Return (2025): https://www.irs.gov/pub/irs-pdf/f1040.pdf
Read from the IRS documents linked above on October 17, 2026. General information, not tax advice. Your own facts decide the outcome, and a preparer, the account provider or the IRS is the right place to confirm anything consequential.