Updated October 18, 2026. Quick answer: Line 6 is the tax on your corrected taxable income, with a code for the method used. Line 7 is nonrefundable credits, line 8 subtracts them, line 10 is other taxes, and line 11 adds lines 8 and 10 to give total tax. Line 9 is reserved and stays empty.
Read box by box from the IRS form text: Form W-2c Notice to Employee.
What lines 6 to 11 ask for
The captions are “Tax. Enter method(s) used to figure tax. See instructions” for line 6, “Nonrefundable credits. If a general business credit carryback is included, check here” for line 7, “Subtract line 7 from line 6.” for line 8, “Reserved for future use” for line 9, “Other taxes” for line 10 and “Total tax. Add lines 8 and 10.” for line 11. This page is part of the Form 1040-X walk-through.
Line 6: tax
The instructions say “Include on line 6 the amount you reported on Schedule 2 (Form 1040), line 3, for the year you are amending.” Then “Figure the tax on your taxable income shown on line 5, column C.” On the method: “Generally, you will use the method(s) you used to figure the tax on your original return.”
“Indicate the method(s) you used to figure the tax entered on line 6, as shown in the chart below.” The chart lists a short code for each method, such as the tax table or a tax worksheet. Take the code from the chart in the instructions. Then “Attach the schedule or form(s), if any, that you used to figure your revised tax.” “Don’t attach worksheets.” The tax line on the return is explained at Form 1040 line 16.
A caution applies to the lines above: “Any changes you made to Form 1040-X, lines 1 through 6, may affect the amount of or cause you to owe alternative minimum tax.”
Line 7: nonrefundable credits
“Enter your total nonrefundable credits in column A.” The instructions define the term: “Nonrefundable credits are those that reduce your tax, but any excess isn’t refunded to you.” If your earlier lines changed, “be sure to refigure your original credits.” “Attach the appropriate forms for the credits you are adding or changing.”
For a late child tax credit claim, “If you are amending a return with a retroactive claim of the child tax credit, you must have an SSN valid for employment issued for the child before the due date for filing the return you are amending, including extensions.” Credits on the return are laid out at Form 1040 lines 19, 20 and 21.
Line 8: subtract line 7 from line 6
The instructions have no separate paragraph for line 8, so the form’s caption is the guide: “Subtract line 7 from line 6.” The caption goes on to say what to enter if the result is zero or less, and the line is figured separately in each column. Computed illustration, not an IRS example: with tax of $3,000 on line 6 and credits of $1,200 on line 7 then line 8 is $3,000 minus $1,200 and the result is $1,800.
Lines 9 and 10: reserved line and other taxes
Line 9: “This line is reserved for future use. Do not enter an amount on this line.”
Line 10: “Enter in column A the amount you reported on the line for total other taxes from Schedule 2 (Form 1040) for the year you are amending.” If earlier lines changed, “you may need to refigure other taxes that were included in the same section on your original return.” Other taxes on the return are explained at Form 1040 lines 22, 23 and 24.
Line 11: total tax
The instructions have no separate paragraph for line 11, so the form’s caption is the guide: “Total tax. Add lines 8 and 10.” Computed illustration, not an IRS example: line 8 of $1,800 and other taxes of $400 on line 10 give a line 11 total of $2,200 ($1,800 plus $400).
Where the number comes from
Column A comes from the matching lines on the return you are amending, and the corrected figures come from the forms for that year. The instructions say “See the tax return for the year you are amending to find the corresponding lines on your original return.”
Where it goes next
Line 11, column C, is compared with the payments. Line 20 says “If line 11, column C, is more than line 19, enter the difference.” Line 21 says “If line 11, column C, is less than line 19, enter the difference.” Those lines are on the lines 18 to 23 page, and the payments that feed line 19 are on the lines 12 to 17 page.
Edition and line numbers
This page reads the December 2025 revision of Form 1040-X, Amended U.S. Individual Income Tax Return, and its December 2025 instructions, the current files irs.gov served on 2026-10-18. Form 1040-X is not tied to one tax year: it amends the return year you enter at the top. The form’s own header says “Attach a completed Form 1040, 1040-SR, or 1040-NR, with your changes, for the return year entered below”. The instructions add “These instructions can be used with the December 2025 and later revisions of Form 1040-X, unless later instructions state otherwise.” Check the revision date printed on the form you are filling in and the return year you are amending, and use the line numbers on that form.
Common mistakes
- Skipping the method code on line 6. The instructions say “Indicate the method(s) you used to figure the tax entered on line 6, as shown in the chart below.”
- Leaving the old credits in place after changing income. The instructions say “be sure to refigure your original credits.”
- Entering an amount on line 9. The instructions say “Do not enter an amount on this line.”
Related: Form 1040 line 16, Form 1040 lines 19, 20 and 21, Form 1040 lines 22, 23 and 24, and Form 1040.
Sources
- Instructions for Form 1040-X, Amended U.S. Individual Income Tax Return (Rev. December 2025): https://www.irs.gov/pub/irs-pdf/i1040x.pdf
- Form 1040-X, Amended U.S. Individual Income Tax Return (Rev. December 2025): https://www.irs.gov/pub/irs-pdf/f1040x.pdf
Read from the IRS documents linked above on October 18, 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.