Updated October 17, 2026. Quick answer: Line 12 is the net investment income tax. The tax is figured on Form 8960, which is attached to the return, and the Form 1040 instructions tell you when to see that form based on the amount on Form 1040, line 11b, and your filing status. The figure that goes on line 12 comes from Form 8960, and line 12 is part of the total other taxes on line 21.
What line 12 asks for
The form’s caption for line 12 reads “Net investment income tax. Attach Form 8960”. The instructions for the line carry the heading “Net Investment Income Tax”. The tax itself is explained on the page about the net investment income tax, and the form is covered on the Form 8960 page.
When to see Form 8960
The instructions say “See Form 8960 and its instructions if the amount on Form 1040, 1040-SR, or” the Form 1040-NR version of the same line, “line 11b, is more than:” and then give one amount for each filing status:
- “$125,000 if married filing separately”
- “$250,000 if married filing jointly”, which the instructions extend with “or qualifying surviving spouse”
- “$200,000 if single or head of household”
There is a second set of amounts for people who file Form 2555. The instructions say “If you file Form 2555, see Form 8960 and its instructions if the amount on” the same line 11b “is more than:” and list “$0 if married filing separately”, “$120,000 if married filing jointly”, and “$70,000 if single or head of household”.
Where the number comes from
Line 12 is not worked out on Schedule 2. The caption tells you to attach Form 8960, and the instructions send you to “Form 8960 and its instructions” to do the figuring. Copy the result from that form onto line 12. Line 11b of Form 1040 is the amount the instructions compare to the filing status amounts above. Neighboring line 11 is the Additional Medicare Tax, and the two are different taxes on different forms. See the page on Schedule 2 lines 10 and 11. Investors who convert a retirement account can read about one way the tax shows up on the page about Roth conversions and the net investment income tax.
Where it goes next
Line 12 is in Part II of Schedule 2. The caption for line 21 reads “Add lines 4, 7 through 16, 18, and 19. These are your total other taxes. Enter here and on Form 1040 or 1040-SR, line 23”. The instructions say the same thing in their general section: “Enter the amount on Schedule 2, line 21, on Form 1040 or 1040-SR, line 23”. The lines that follow are on the page for Schedule 2 lines 13 to 16. For the schedule as a whole, see Schedule 2 (Form 1040), and for the form it attaches to, see Form 1040.
Edition and line numbers
This page reads the 2025 Schedule 2 (Form 1040) and the 2025 Form 1040 instructions, the current files irs.gov served on 2026-10-17. They are the files for the tax year 2025 return, filed in 2026. The schedule says “Attach to Form 1040, 1040-SR, or 1040-NR.” Its line instructions are part of the Form 1040 instructions, under the heading “Instructions for Schedule 2”. Check the tax year printed on the schedule you are filling in and use the line numbers on that year’s schedule, because a different year’s schedule can number or word its lines differently.
Common mistakes
- Skipping Form 8960 because the tax is not on the schedule itself. The caption says “Net investment income tax. Attach Form 8960”.
- Using the wrong filing status amount. The instructions list “$250,000 if married filing jointly” and “$200,000 if single or head of household” as separate amounts, so match the amount to your status.
- Forgetting the second set of amounts when you file Form 2555. The instructions say “If you file Form 2555, see Form 8960 and its instructions if the amount on” line 11b is more than a different amount.
Related: net investment income tax, Form 8960, Roth conversions and the net investment income tax, and Form 1040.
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- Instructions for Form 1040 and Form 1040-SR (2025): https://www.irs.gov/pub/irs-pdf/i1040gi.pdf
- Schedule 2 (Form 1040), Additional Taxes (2025): https://www.irs.gov/pub/irs-pdf/f1040s2.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.