How to Find Total Income Tax on Form 1040: Line 24

Your total tax on Form 1040 is on Line 24. It equals Line 22 (the tax on your income after nonrefundable credits) plus Line 23 (additional taxes carried over from Schedule 2, Part II).¹ That single number is your complete federal tax obligation for the year, before any credit for what you have already paid in through withholding or estimated payments.

Many people assume Line 16 is their total tax because it is labeled “Tax” and sits prominently on the form. It isn’t. Line 16 is only the tax computed on your taxable income. Everything else the IRS treats as part of your annual bill, including self-employment tax, the net investment income tax, the additional Medicare tax, and the 10% penalty on early retirement withdrawals, gets added further down the form before you arrive at Line 24.

Where Line 24 Sits on the Form

Form 1040 moves from income down to total tax in a fixed sequence. Line 15 is your taxable income. Line 16 is the tax calculated on that taxable income. Line 17 brings in the alternative minimum tax and a few other items from Schedule 2, Part I. Line 18 adds Lines 16 and 17. Lines 19 through 21 subtract nonrefundable credits, producing Line 22. Line 23 carries over the additional taxes from Schedule 2, Part II. Line 24 is Line 22 plus Line 23.¹

If you want to verify Line 24 on your own return, the arithmetic is simple: add the dollar amount on Line 22 to the dollar amount on Line 23. If those two lines add up to Line 24, the total tax figure itself is correct, whatever is or isn’t feeding into it.

Why Line 24 Often Exceeds Line 16

For a W-2 employee with straightforward income, no credits worth much, and nothing unusual on the investment or retirement side, Line 16 and Line 24 can look nearly identical. The gap widens quickly in a few common situations:

You had self-employment income and owe self-employment tax.
Your investment income and modified AGI crossed the net investment income tax threshold.
Your wages or self-employment income passed the additional Medicare tax threshold.
You took an early distribution from a retirement account.
You owed household employment taxes for a nanny or housekeeper.
The alternative minimum tax applied to you.

If your tax software is showing a surprisingly high total tax, Schedule 2 is where to look. It itemizes everything that was added between Line 16 and Line 24.

What Builds Line 22

Line 22 is the income tax piece, after credits. Three things determine it.

Line 16: tax on your taxable income. If your taxable income is under $100,000, the amount comes from the IRS tax tables. If it is $100,000 or more, it comes from the Tax Computation Worksheet, which applies the graduated brackets directly.² If you had qualified dividends or long-term capital gains, Line 16 comes instead from the Qualified Dividends and Capital Gain Tax Worksheet, which taxes those gains at 0%, 15%, or 20% depending on your income and filing status and blends the result with the ordinary-rate tax on the rest of your income.³

Line 17: alternative minimum tax and other Schedule 2, Part I items. The AMT is a parallel calculation on Form 6251. If it produces a higher tax than your regular tax, you owe the difference. Common AMT triggers include exercising incentive stock options, holding private activity bonds, and large state and local tax deductions.⁴ Most taxpayers never owe AMT, but the amount, if any, lands on Line 17 and gets added to Line 16 to produce Line 18.⁵

Lines 19 through 21: nonrefundable credits. Line 19 holds the child tax credit and credit for other dependents. Line 20 holds other nonrefundable credits reported through Schedule 3, which include the foreign tax credit, the child and dependent care credit, education credits, the saver’s credit, and residential clean energy credits.⁶ Line 21 is the sum, and it gets subtracted from Line 18 to produce Line 22. These credits reduce your tax dollar for dollar but cannot drive it below zero.

What Builds Line 23

Line 23 is a catch-all for taxes that are calculated on separate forms and have nothing to do with the tax brackets. They flow through Schedule 2, Part II and land on Line 23 of Form 1040.⁵ For most people who owe anything on Line 23, one or two of the following account for nearly all of it.

Self-Employment Tax

If you earned money as a sole proprietor, freelancer, or independent contractor, you owe self-employment tax covering both the employer and employee shares of Social Security and Medicare. The combined rate is 15.3%: 12.4% for Social Security and 2.9% for Medicare.⁷ The Social Security portion applies only up to the annual wage base; the Medicare portion applies to all net earnings. You calculate it on Schedule SE, and half of it is deductible as an adjustment to income on the front of Form 1040.

Net Investment Income Tax

The net investment income tax is 3.8% on the lesser of your net investment income or the amount your modified AGI exceeds the threshold for your filing status: $200,000 single, $250,000 married filing jointly, $125,000 married filing separately. These thresholds are not indexed to inflation. Investment income for this purpose includes interest, dividends, capital gains, rental income, and royalties. You calculate the tax on Form 8960.⁸

Additional Medicare Tax

An extra 0.9% Medicare tax applies to wages and self-employment income above $200,000 single, $250,000 joint, and $125,000 married filing separately. Employers withhold it once wages pass $200,000 regardless of filing status, so married couples sometimes find they had too much or too little withheld. Form 8959 reconciles the difference.⁹

Early Distribution Penalty

If you withdrew money from a traditional IRA or other qualified retirement plan before age 59½, the taxable portion is generally hit with a 10% additional tax, reported on Form 5329. Exceptions exist for a first home purchase, certain medical expenses, substantially equal periodic payments, and others.¹⁰

Household Employment Taxes

If you paid a nanny, housekeeper, or other household employee cash wages at or above the annual threshold, you owe the employer share of Social Security and Medicare tax on those wages, and possibly federal unemployment tax. These are figured on Schedule H and roll into Line 23.¹¹

What Line 24 Is Not

Line 24 is not your refund, and it is not the balance you write a check for. It is your tax before the form credits you for anything you have already paid. The lines after it (25 through 33) tally federal income tax withholding from your W-2s and 1099s, estimated tax payments, and refundable credits such as the earned income credit and the additional child tax credit. Line 24 compared against those payments is what produces either a refund or an amount owed.

So if someone asks what your federal income tax was for the year, Line 24 is the answer. If they ask what you paid or got back at filing time, that is a different number further down the form.

1
Internal Revenue Service. Form 1040
2
Internal Revenue Service. Publication 1040 (2025), Tax and Earned Income Credit Tables
3
Internal Revenue Service. Instructions for Form 1040 – Section: Line 16 Tax
4
Internal Revenue Service. Instructions for Form 6251 (2025)
5
Internal Revenue Service. 2025 Schedule 2 (Form 1040)
6
Internal Revenue Service. Instructions for Form 1040 (2025)
7
Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes)
8
Internal Revenue Service. Questions and Answers on the Net Investment Income Tax
9
Internal Revenue Service. Questions and Answers for the Additional Medicare Tax
10
Internal Revenue Service. Instructions for Form 5329 (2025) – Section: Part I Additional Tax on Early Distributions
11
Internal Revenue Service. Publication 926 (2026), Household Employers Tax Guide