Updated October 17, 2026. Quick answer: Lines 6f to 6k continue the Other nonrefundable credits group on Schedule 3. Each line takes the result of one named form: Form 8936 for the clean vehicle credit, Form 8396 for the mortgage interest credit, Form 8859 for the D.C. first-time homebuyer credit, Form 8834 for the qualified electric vehicle credit, Form 8911 for refueling property and Form 8912 for tax credit bonds.
More IRS forms and schedules for individual filers, read line by line: Form 8396 instructions.
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 6f: clean vehicle credit
The form’s caption reads “Clean vehicle credit. Attach Form 8936”. The instruction for the line is “Enter the personal use part of any credit for new clean vehicles. See Form 8936, Part III.”
Lines 6g and 6h: mortgage interest and D.C. homebuyer credits
Line 6g is captioned “Mortgage interest credit. Attach Form 8396”. The instructions say “Enter any mortgage interest credit if a state or local government gave you a mortgage credit certificate. See Form 8396.”
Line 6h is the District of Columbia first-time homebuyer credit, and its caption ends “homebuyer credit. Attach Form 8859”. The instructions limit it: “You can’t claim the District of Columbia first-time homebuyer credit for a home you bought after 2011.” “You can claim it only if you have a credit carryforward from 2024. See Form 8859.”
Lines 6i to 6k: electric vehicle, refueling property and tax credit bonds
Line 6i is captioned “Qualified electric vehicle credit. Attach Form 8834”. The instructions say “Enter any qualified electric vehicle credit.” “You can’t claim this credit for a vehicle placed in service after 2006.” “You can claim this credit only if you have an electric vehicle passive activity credit carried forward from a prior year. See Form 8834.”
Line 6j is captioned “Alternative fuel vehicle refueling property credit. Attach Form 8911”, and the instruction is “Enter any alternative fuel vehicle refueling property credit. See Form 8911.”
Line 6k is captioned “Credit to holders of tax credit bonds. Attach Form 8912”, and the instruction is “Enter any credit to holders of tax credit bonds. See Form 8912.”
Where the number comes from
As with lines 6a to 6e, nothing is figured on Schedule 3 itself. Each line takes the result from the form named in its caption. The earlier lines of the group are covered on the page for Schedule 3 lines 6a to 6e.
Where it goes next
Lines 6f to 6k are added into line 7, whose caption reads “Total other nonrefundable credits. Add lines 6a through 6z”. The rest of line 6 is on Schedule 3 lines 6l, 6m and 6z, and the line 7 step is on Schedule 3 lines 7 and 8. 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 the whole vehicle credit on line 6f. The instruction asks only for “Enter the personal use part of any credit for new clean vehicles.”
- Claiming the D.C. first-time homebuyer credit for a recent purchase. The instructions say “You can’t claim the District of Columbia first-time homebuyer credit for a home you bought after 2011.”
- Claiming the qualified electric vehicle credit for a new vehicle. The instructions say “You can’t claim this credit for a vehicle placed in service after 2006.”
Related: Schedule 3 lines 6a to 6e, 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.