Updated October 17, 2026. Quick answer: Line 17a is for recapture of certain other credits, and you list the type, form number and amount. Line 17b is recapture of a federal mortgage subsidy, which can apply if you sold your home. Both lines are part of the other additional taxes that are added up on line 18.
Line 17a: recapture of other credits
The form’s caption reads “Recapture of other credits. List type, form number, and amount”. The instructions open with “Recapture of the following credits.” and then number the credits that belong on this line. Two of them name a credit and a form: “New markets credit (see Form 8874).” and “Credit for employer-provided childcare facilities (see Form 8882).” The list also includes amounts that come from Form 4255 and from Form 3468, each with an identifying label that the instructions spell out. Read that list for the exact wording of each label before you write an entry.
Line 17b: recapture of a federal mortgage subsidy
The caption reads “Recapture of federal mortgage subsidy. If you sold your home, see instructions”. The instructions explain: “If you sold your home in 2025 and it was financed (in whole or in part) from the proceeds of any tax-exempt qualified mortgage bond or you claimed the mortgage interest credit, you may owe a recapture tax on the mortgage subsidy.” They then add “See Form 8828.” Form 8828 is the form the instructions point you to for this line. If you itemize deductions, the related mortgage interest rules are on the Schedule A page.
Where the number comes from
For line 17a, the amount comes from the credit forms the list names, and you write the type and form number beside it, as the caption says. For line 17b, the instructions send you to Form 8828.
Where it goes next
Line 17a and line 17b are two of the entries added on line 18. The caption for line 18 reads “Total additional taxes. Add lines 17a through 17z”. Line 18 is then included in line 21, and the lines in between are covered on the page for lines 17z and 18. Line 21 ends up on the Form 1040 line described on the page about Form 1040 lines 22, 23 and 24. The group before this one is on lines 13 to 16, and the schedule overall is on the Schedule 2 (Form 1040) page.
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
- Leaving off the type and form number on line 17a. The caption says “List type, form number, and amount”.
- Ignoring line 17b after selling a home. The instructions say “you may owe a recapture tax on the mortgage subsidy.”
- Skipping the form for line 17b. The instructions end the paragraph with “See Form 8828.”
Related: Schedule A, Form 1040 lines 22, 23 and 24, Form 1040, and Form 1040 line by line.
Sources
- 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.