Updated October 16, 2026. Quick answer: Box 17 of Schedule K-1 (Form 1120-S) is the Other information box, and the 2025 instructions define many codes beyond the ones with their own pages. The table below gives the title of each remaining code and the form or line the instructions name. Codes the IRS marks “Reserved for future use” are grouped after it.
Remaining box 17 codes
Codes A and B, U, V, and K through O are covered on their own pages. The rest are below, in the order the instructions print them. The code letter is the one printed in box 17 of the K-1. Every other box is set out on the Schedule K-1 (Form 1120-S) boxes overview.
| Code | Title in the instructions | What the instructions say |
|---|---|---|
| C | “Qualified rehabilitation expenditures (other than rental real estate)” | “The corporation will report your share of qualified rehabilitation expenditures and other information you need to complete Form 3468 for property not related to rental real estate activities” |
| D | “Basis of energy property.” | “If the corporation provides an attached statement for code D, use the information on the statement to complete the applicable energy credit in Part VI of Form 3468.” |
| E, F | “Recapture of low-income housing credit.” | “All other recapture of low-income housing credits will be identified by code F.” |
| G | “Recapture of investment credit.” | “The corporation will provide any information you need to figure your recapture tax on Form 4255” |
| H | “Recapture of other credits.” | “the corporation will report any information you need to figure the recapture of other credits” |
| I | “Look-back interest” “completed long-term contracts.” | “Use Form 8697, Interest Computation Under the Look-Back Method for Completed Long-Term Contracts, to report any such interest.” |
| J | “Look-back interest” “income forecast method.” | “Use Form 8866, Interest Computation Under the Look-Back Method for Property Depreciated Under the Income Forecast Method, to report any such interest.” |
| P | Interest allocable to production expenditures. | “The corporation will report any information you need relating to interest you are required to capitalize under section 263A for production expenditures.” |
| Q | Capital construction fund (CCF) nonqualified withdrawals. | “Include the tax and interest on Schedule 2 (Form 1040), line 17z.” |
| R | “Depletion information” for oil and gas | “Reduce the basis of your stock by the amount of this deduction up to the extent of your adjusted basis in the property.” |
| AA | “Excess taxable income.” | “Report this amount of excess taxable income in column (c) of Form 8990, Schedule B, line 45, if you are required to file Form 8990.” |
| AB | “Excess business interest income.” | “Report this amount of excess business interest income in column (d) of Form 8990, Schedule B, line 45, if you are required to file Form 8990.” |
| AC | “Gross receipts for section 448(c).” | “Use the gross receipts amount to figure the business interest expense you can deduct, if applicable.” |
| AJ | “Excess business loss limitation.” | “You can use this, along with other information, to figure any excess business loss limitation.” |
| AN | “Farming and fishing income.” | “report this income, as an item of information, on Schedule E (Form 1040), Part V, line 42.” |
| AP | “Inversion gain.” | “The corporation will provide a statement showing the amounts of each type of income or gain that is included in inversion gain.” |
| AS | “Qualifying advanced coal project property and qualifying gasification project property.” | For advanced coal project property, “use the amounts the corporation provides you to figure the amounts to report on Form 3468, Part II, Section A, lines 1a, 2a, and 3a.” For gasification project property, the same instruction points to Form 3468, Part II, Section B, lines 4a and 5a. |
| AT | Qualifying advanced energy project property. | “Use the amounts the corporation provides you to figure the amounts to report on Form 3468, Part III, line 1a.” |
| AU | Advanced manufacturing investment property. | “Use the amounts the corporation provides you to figure the amount to report on Form 3468, Part IV, line 1b.” |
| AV | “Clean electricity investment.” | “Use the amounts the corporation provides you to figure the amount to report on Form 3468, Part V, line 1a.” |
| AW | “Reportable transactions.” | “Any information you need to complete a disclosure statement for reportable transactions in which the corporation participates.” |
Credit and energy codes: C, D, E, F, G, H, AS to AV
Several codes feed Form 3468 or credit recapture. For code C, the rental real estate version is a different box: “Your share of qualified rehabilitation expenditures related to rental real estate activities is reported in box 13 using code E.” “Combine the expenditures (for Form 3468 reporting) from box 13, code E, and from box 17, code C.”
For codes E and F, the instructions add: “Keep a separate record of each type of recapture so that you will be able to correctly figure any credit recapture that may result from the disposition of all or part of your corporate stock.”
Business interest, loss and farming codes: AA, AB, AC, AJ, AN
Codes AA, AB and AC feed Form 8990 and the business interest limit. For code AJ, “If the corporation has deductions attributable to a business activity, it’ll provide a statement” showing the aggregate gross income or gain and the aggregate deductions from the business activity. The measure is explained by the reference the instructions give: “See section 461(l) and the Instructions for Form 461 for details.”
For code AN, the instructions split individuals from estates and trusts. “Don’t report this income elsewhere on Form 1040 or 1040-SR.” “For a shareholder that is an estate or a trust, report this income to the beneficiaries, as an item of information, on Schedule K-1 (Form 1041), Beneficiary’s Share of Income, Deductions, Credits, etc.” Farm entities are discussed on the farm LLC or partnership page, and the return line is on Schedule E (Form 1040).
Code BA: domestic research or experimental expenditures
“P.L. 119-21 added section 174A, which pertains to domestic research and experimental expenditures.” “Section 174A(a) allows a deduction for domestic research and experimental expenditures paid or incurred during the tax year for tax years beginning after 2024.”
“Under section 174A(c), you may elect to charge such expenditures to a capital account rather than deducting them and be allowed an amortization deduction of such expenditures proportionately over a period of not less than 60 months.” “For more information about section 174A, and the provisions contained in P.L. 119-21, sections 70302(f)(1) and (2), see Rev. Proc. 2025-28.”
Amortization is reported on Form 4562.
Code ZZ: other
“Any other information you may need to file your return not shown elsewhere on Schedule K-1.” The instructions list two examples. The first: “P.L.119-21 enacted new section 139L that allows a qualified lender to exclude 25% of the interest income on qualified loans secured by rural or agricultural real property.” “For more information see Notice 2025-71.”
The second: “The S corporation will provide the information you need to make an election under section 1062 to pay tax on the gain from the sale or exchange of qualified farmland property to qualified farmers in installments.”
Reserved codes
| Codes | As printed in the instructions |
|---|---|
| S and T | “Codes S and T. Reserved for future use.” |
| W through Z | “Codes W through Z. Reserved for future use.” |
| AD through AI | “Codes AD through AI. Reserved for future use.” |
| AK through AM | “Codes AK through AM. Reserved for future use.” |
| AO | “Code AO. Reserved for future use.” |
| AQ and AR | “Codes AQ and AR. Reserved for future use.” |
| AX through AZ | “Codes AX through AZ. Reserved for future use.” |
| BB through BD | “Codes BB through BD. Reserved for future use.” |
Limits and the corporation’s reporting
The instructions put the limits in a fixed order: “These limitations and the order in which you must apply them are as follows: the basis limitations, the at-risk limitations, the passive activity limitations, and the excess business loss limitations.” The amounts printed in Part III are before any of them. “The amounts shown in boxes 1 through 17 reflect your share of income, loss, deductions, credits, and other items from corporate business or rental activities without reference to limitations on losses, credits, or other items that may have to be adjusted”.
Which revision applies
The edition read for this page is the 2025 Shareholder’s Instructions for Schedule K-1 (Form 1120-S) and the 2025 Schedule K-1 (Form 1120-S) itself, which are the revisions irs.gov served when they were read on 2026-10-16. Check the revision printed on the Schedule K-1 you received and the matching instructions, because a later edition can change the box layout, the code letters and the reporting lines.
Common mistakes
- Reporting the same rehabilitation expenditures twice. The instructions say expenditures related to rental real estate are reported in box 13 with code E and other expenditures in box 17 with code C, and that the two are combined for Form 3468.
- Putting code AN income on the main return lines. The instructions say an individual reports it as an item of information on Schedule E (Form 1040), Part V, line 42, and not elsewhere on Form 1040 or Form 1040-SR.
- Treating a code ZZ entry as optional because it has no named line. The instructions define code ZZ as other information you may need to file your return, and give the section 1062 farmland election as one example.
Related: Schedule E (Form 1040), Form 4562 depreciation and amortization, farm LLC or partnership basics, and Form 8582 passive activity loss limitations.
Sources
- 2025 Shareholder’s Instructions for Schedule K-1 (Form 1120-S): https://www.irs.gov/pub/irs-pdf/i1120ssk.pdf
- Schedule K-1 (Form 1120-S) (2025), Shareholder’s Share of Income, Deductions, Credits, etc.: https://www.irs.gov/pub/irs-pdf/f1120ssk.pdf
Read from the IRS documents linked above on October 16, 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.