What this line means
Your total federal tax liability after all credits and additional taxes. This combines the income tax from line 16, minus nonrefundable credits (lines 19-21), plus additional taxes from Schedule 2 (self-employment tax, early distribution penalties, net investment income tax, additional Medicare tax). This is the number your payments are compared against to determine your refund or balance due.
Does this apply to you?
- You have a tax liability from any source
- You owe the 10% early distribution penalty on an IRA or pension withdrawal before age 59½
- You owe net investment income tax (3.8% on investment income above AGI thresholds)
- You owe additional Medicare tax (0.9% on earnings above $200,000 single / $250,000 married filing jointly)
- You claimed nonrefundable credits that reduce your tax below line 16
Easy to overlook
Net investment income tax applies above AGI thresholds The 3.8% net investment income tax (NIIT) applies to the lesser of your net investment income or the amount your MAGI exceeds $200,000 (single) or $250,000 (married filing jointly). Seniors with significant investment portfolios — dividends, capital gains, rental income — often owe this additional tax. It is calculated on Form 8960 and flows to Schedule 2. 1 IRS Form 1040-SR Instructions — Line 24
Early distribution penalty has exceptions for seniors The 10% early distribution penalty on IRA or retirement plan withdrawals before age 59½ does not apply to most seniors using Form 1040-SR, since the form is for filers 65 or older. However, if you are filing 1040-SR because your spouse is 65+ but you are under 59½ and took an early distribution from your own retirement account, the penalty still applies to your distribution. 2 General filing pattern — omitting Schedule 2 taxes
Watch out for this
Skipping Schedule 2 when you have additional taxes. Schedule 2 captures taxes beyond the basic income tax — including the NIIT, additional Medicare tax, and early distribution penalties. If any of these apply, line 24 is higher than line 16, and omitting Schedule 2 understates your total tax.
Footnotes
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IRS Form 1040-SR Instructions, Line 24. https://www.irs.gov/instructions/i1040sr ↩
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IRS Form 5329 Instructions, Additional Tax on Early Distributions. https://www.irs.gov/instructions/i5329 ↩