Updated October 18, 2026. Quick answer: Part IV is the previously owned clean vehicle credit. Line 14 is the total from Schedule A, lines 15 to 17 test it against the tax on your return, and line 18 is the smaller of line 14 or line 17. Line 18 goes to Schedule 3, line 6m.
What lines 14 to 18 ask for
Part IV is headed “Credit for Previously Owned Clean Vehicles”. Line 14 reads “Enter the total credit amount figured in Part IV of Schedule(s) A (Form 8936)”. Line 15 reads “Enter the amount from Form 1040, 1040-SR, or 1040-NR, line 18” and line 16 reads “Personal credits from Form 1040, 1040-SR, or 1040-NR (see instructions)”. The instructions say “Use Parts I and IV of Form 8936 to claim the credit for previously owned clean vehicles.” “Use Parts I and IV of Schedule A (Form 8936) to figure the previously owned clean vehicle credit amount.”
Where the numbers come from
Line 14 comes from Schedule A. Line 15 is the line 18 amount on your return, explained at Form 1040 lines 17 and 18. For line 16 the instructions say “Enter the total, if any, credits from Schedule 3 (Form 1040), lines 1 through 4, 5b, 6d, and 6I.” Part I of the form, covered on the Part I, lines 1 to 5 page, supplies the income test.
Lines 17 and 18
Line 17 says “Subtract line 16 from line 15.” “If zero or less, enter -0- and stop here. You can’t claim the Part IV credit”. Line 18 says “Enter the smaller of line 14 or line 17 here and on Schedule 3 (Form 1040), line 6m.” “If line 17 is smaller than line 14, see instructions”.
If part of the credit goes unused
The line 18 instructions say “If you cannot use part of the credit because of the tax liability limit, the unused credit is lost.” “The unused credit cannot be carried back or forward to other tax years.”
The credit and who can claim it
On the amount, the instructions say “The credit is equal to the lesser of $4,000 or 30% of the sales price of a previously owned clean vehicle you acquired and placed in service during your tax year.” They list conditions, including “You are an individual.” “You can’t be claimed as a dependent by another taxpayer.” “You have not claimed another previously owned clean vehicle credit in the 3 years before the purchase date.” On the vehicle, they list “Has a sales price that does not exceed $25,000;” and “Was purchased from a dealer and was the first transfer since August 16, 2022, to an individual eligible to claim the credit;”
The income limit and the date
The Part IV income limit is stated in running prose: “Your modified adjusted gross income (AGI) for 2024 or 2025 is not more than $75,000 ($150,000 if married filing jointly or a qualifying surviving spouse; $112,500 if head of household).” On the date, a caution reads “You cannot claim the previously owned clean vehicle credit for any vehicle acquired after September 30, 2025.”
Where it goes next
Line 18 goes to Schedule 3, line 6m, covered at Schedule 3 lines 6l, 6m and 6z. The new vehicle credit is on the Part III, lines 9 to 13 page, and the whole form is walked through at Form 8936.
Edition and line numbers
This page reads the 2025 Form 8936, Clean Vehicle Credits and its 2025 instructions, the current files irs.gov served on 2026-10-18. They are the files for the tax year 2025 return, filed in 2026. The form’s own header says “Attach to your tax return.” Check the tax year printed on the form you are filling in and use the line numbers on that year’s form, because a different year’s form can number or word its lines differently.
Common mistakes
- Entering the full Schedule A amount when the tax limit bites. Line 18 says “Enter the smaller of line 14 or line 17 here and on Schedule 3 (Form 1040), line 6m.”
- Expecting to use an unused amount later. The instructions say “The unused credit cannot be carried back or forward to other tax years.”
- Overlooking the earlier-claim rule. The instructions list “You have not claimed another previously owned clean vehicle credit in the 3 years before the purchase date.”
Related: Form 8936, Schedule 3 lines 6l, 6m and 6z, Form 1040 lines 17 and 18, and Form 1040 lines 19, 20 and 21.
Sources
- Instructions for Form 8936, Clean Vehicle Credits (and Schedule A (Form 8936), Clean Vehicle Credit Amount) (2025): https://www.irs.gov/pub/irs-pdf/i8936.pdf
- Form 8936, Clean Vehicle Credits (2025): https://www.irs.gov/pub/irs-pdf/f8936.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.