What this line means
Your federal income tax calculated from your taxable income on line 15. This is not a simple flat percentage — it uses the progressive tax brackets where different portions of your income are taxed at different rates (10%, 12%, 22%, 24%, 32%, 35%, 37%). If you have qualified dividends or long-term capital gains, those portions are taxed at lower rates (0%, 15%, or 20%) using the Qualified Dividends and Capital Gain Tax Worksheet.
Does this apply to you?
- Every filer with taxable income on line 15 completes this line
- You use the Tax Table (if taxable income is under $100,000) or Tax Rate Schedule (if $100,000 or more)
- If you have qualified dividends or capital gains, you use the special worksheet or Schedule D Tax Worksheet instead
Easy to overlook
Qualified dividends and long-term capital gains get their own lower rates Line 16 is not just a straight lookup from the tax table. If you have qualified dividends (line 3a) or net long-term capital gains, you use the Qualified Dividends and Capital Gain Tax Worksheet to calculate a blended tax that applies lower rates to those portions. This can save thousands of dollars compared to taxing everything at ordinary rates. 1 IRS Tax Tables and Tax Rate Schedules
The tax brackets are marginal, not flat A common misconception is that your entire income is taxed at your “tax bracket rate.” In reality, only the income within each bracket is taxed at that rate. A single filer with $50,000 taxable income does not pay 22% on $50,000 — they pay 10% on the first $11,925, 12% on the next $36,550, and 22% only on the remaining $1,525. 2 General filing pattern — using wrong tax table or filing status
Watch out for this
Using the wrong filing status column in the tax table. The tax table has separate columns for single, married filing jointly, married filing separately, and head of household. Using the wrong column produces the wrong tax amount, and the difference can be significant — especially between single and head of household, where the brackets are wider for head of household.
Footnotes
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IRS Form 1040 Instructions, Tax Table and Tax Computation Worksheet. https://www.irs.gov/instructions/i1040 ↩
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IRS Form 1040 Instructions. See also IRS Publication 17, Your Federal Income Tax. https://www.irs.gov/pub/irs-pdf/p17.pdf ↩