15 — Taxable Income Updated for tax year 2025

What this line means

Your adjusted gross income minus your total deductions — the final income figure that determines your federal income tax. This is the number that gets run through the tax brackets. If your deductions exceed your AGI, taxable income is zero (you cannot have negative taxable income). This is the most important number on your return because it directly drives your tax bill.

Does this apply to you?

• Every filer completes this line — it is line 11b minus line 14, or zero if the result is negative
• This is the number your tax bracket is based on
• Tax software calculates this automatically

Easy to overlook

Taxable income is much lower than what you actually earned Between above-the-line adjustments, the standard deduction, and possibly the QBI deduction, taxable income can be significantly less than your total earnings. A single filer earning $60,000 in wages with the standard deduction has a taxable income of $44,250. Understanding this gap helps you estimate your actual tax burden more accurately. ¹ [SOURCE: IRS Form 1040 instructions — Line 15 computation]

Zero taxable income does not always mean zero tax In rare cases, you can have zero on line 15 but still owe tax through the Alternative Minimum Tax (AMT) on Schedule 2, self-employment tax, or the tax on early retirement plan distributions. Line 15 being zero eliminates regular income tax but not all taxes that appear on your return. ² [SOURCE: General filing pattern — taxable income confused with total income]

Watch out for this

Confusing taxable income with AGI or total income when applying for mortgages, financial aid, or government programs. Each program specifies which income figure it uses. FAFSA uses AGI. Mortgage lenders use gross income. ACA subsidies use modified AGI. Using line 15 when a program asks for AGI (line 11a) or vice versa creates eligibility errors.

Related lines on your return

• Line 11b — Form 1040 — AGI carried forward; the starting point before deductions
• Line 14 — Form 1040 — Total deductions subtracted from AGI
• Line 16 — Form 1040 — Tax; calculated from this taxable income amount