Updated October 17, 2026. Quick answer: Line 6l takes the amount from Form 8978, line 14, which relates to a partner’s audit liability, and has a worksheet for a negative amount. Line 6m takes the credit for previously owned clean vehicles from Form 8936, Part IV. Line 6z is to be left blank.
Business use of your home (Form 8829), the saver’s credit (Form 8880), clean vehicle credits (Form 8936) and amended returns (Form 1040-X), read line by line: Form 8936, Form 8936 Part I and Form 8936 line 18.
Line 6l: the Form 8978 amount
The form’s caption reads “Amount on Form 8978, line 14. See instructions”. The instructions say “Enter the amount from Form 8978, line 14 (relating to partner’s audit liability under section 6226).” The answer depends on the sign of that amount. For a negative one: “If the amount on Form 8978, line 14, is negative, complete the following worksheet to figure the amount to enter on line 6l.”
For a positive one, the instructions send you elsewhere: “If the amount on Form 8978, line 14, is positive, see the instructions for Form 1040 or 1040-SR, line 16.” The worksheet is titled the Negative Form 8978 Adjustment Worksheet for Schedule 3, line 6l, and is printed in the Form 1040 instructions right after the line 6 text. Work through it there rather than from a summary.
Line 6m: previously owned clean vehicles
Line 6m is captioned “Credit for previously owned clean vehicles. Attach Form 8936”. The instruction reads “Enter any credit for previously owned clean vehicles. See Form 8936, Part IV”.
Line 6z: leave it blank
Line 6z carries the caption “Other nonrefundable credits. List type and amount:”, but the instructions are plain: “Leave line 6z blank.”
Where the number comes from
Line 6l comes from Form 8978 (and the worksheet when that amount is negative), and line 6m comes from Form 8936. Neither is figured on Schedule 3 itself. The earlier lines of the group are on Schedule 3 lines 6a to 6e and Schedule 3 lines 6f to 6k.
Where it goes next
Lines 6l and 6m feed line 7, whose caption reads “Total other nonrefundable credits. Add lines 6a through 6z”. See Schedule 3 lines 7 and 8 for that step. The Form 1040 lines 19, 20 and 21 page shows where the Schedule 3 total lands on the return.
Edition and line numbers
This page reads the 2025 Schedule 3 (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.” Schedule 3 has no separate instructions booklet. Its line instructions are part of the Form 1040 instructions, under the heading “Instructions for Schedule 3”. 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
- Entering a negative Form 8978 amount on line 6l without the worksheet. The instructions say “complete the following worksheet to figure the amount to enter on line 6l.”
- Treating a positive Form 8978 amount as a line 6l entry. The instructions say “is positive, see the instructions for Form 1040 or 1040-SR, line 16.”
- Listing a credit on line 6z. The instructions say “Leave line 6z blank.”
Related: Form 1040 line 16, Form 1040 lines 19, 20 and 21, and Form 1040.
Sources
- Instructions for Form 1040 and Form 1040-SR (2025): https://www.irs.gov/pub/irs-pdf/i1040gi.pdf
- Schedule 3 (Form 1040), Additional Credits and Payments (2025): https://www.irs.gov/pub/irs-pdf/f1040s3.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.