Updated September 29, 2026. Quick answer: Box 12 of a Schedule K-1 (Form 1041) holds alternative minimum tax (AMT) items in codes A through J. Codes A through I feed Form 6251, and code J, exclusion items, helps figure a minimum tax credit for the next year on Form 8801.
Every Box 12 code
The instructions read here are the 2025 edition of the IRS Instructions for Schedule K-1 (Form 1041) for a Beneficiary Filing Form 1040 or 1040-SR (Catalog Number 11374Z, dated March 13, 2025), the edition served at the IRS standing PDF address when read on September 29, 2026. They are written for the beneficiary; the fiduciary’s own instructions are in the Instructions for Form 1041. The form’s page 2 lists the codes:
| Code | Form label | Report on (form’s code list) |
|---|---|---|
| A | Adjustment for minimum tax purposes | Form 6251, line 2j |
| B | AMT adjustment attributable to qualified dividends | See the beneficiary’s instructions and the Instructions for Form 6251 |
| C | AMT adjustment attributable to net short-term capital gain | See the beneficiary’s instructions and the Instructions for Form 6251 |
| D | AMT adjustment attributable to net long-term capital gain | See the beneficiary’s instructions and the Instructions for Form 6251 |
| E | AMT adjustment attributable to unrecaptured section 1250 gain | See the beneficiary’s instructions and the Instructions for Form 6251 |
| F | AMT adjustment attributable to 28% rate gain | See the beneficiary’s instructions and the Instructions for Form 6251 |
| G | Accelerated depreciation | See the beneficiary’s instructions and the Instructions for Form 6251 |
| H | Depletion | See the beneficiary’s instructions and the Instructions for Form 6251 |
| I | Amortization | See the beneficiary’s instructions and the Instructions for Form 6251 |
| J | Exclusion items | 2026 Form 8801 |
Codes A through I, for Form 6251
“The information reported in box 12, codes A through I, is used to prepare your Form 6251.” “Code A, Adjustment for minimum tax purposes, is the total amount reported on Form 6251, line 2j.” “Codes B through F represent the portion, if any, of the amount included in code A.”
Codes B through F, and G through I
“If you have an amount in box 12 with code B, C, D, E, or F, see the instructions for lines 13, 14, and 15 of Form 6251.” “Include the amount with any of these codes on the applicable line of Form 6251.” The last sentence is the instruction for codes G through I.
Code J, exclusion items
“If you pay AMT in 2025, the amount in box 12, code J, will help you figure any minimum tax credit for 2026.” The instructions refer to “the 2026 Form 8801, Credit for Prior Year Minimum Tax”. CMG’s AMT credit recovery page covers the credit and the AMT exemption page the exemption figures.
Common mistakes
- Reading Box 12 as tax you owe. It holds adjustments and items used to prepare Form 6251.
- Adding code A to codes B through F. The instruction says B through F are portions of the amount included in A.
- Ignoring code J in a year you pay AMT. The instruction ties it to a later minimum tax credit.
Related: Schedule K-1 Box 11 Codes E and F: NOL Carryover, Schedule K-1 Box 13 Codes A and B: Estimated Tax Credit, AMT credit recovery, and the AMT exemption.
Every box and code in one place: the Schedule K-1 (Form 1041) boxes table. What a K-1 from an estate reports overall is on the Schedule K-1 for estates page.
Sources
- IRS, Instructions for Schedule K-1 (Form 1041) for a Beneficiary Filing Form 1040 or 1040-SR (2025): https://www.irs.gov/pub/irs-pdf/i1041sk1.pdf
- IRS, Schedule K-1 (Form 1041) 2025, Beneficiary’s Share of Income, Deductions, Credits, etc., page 2 code list: https://www.irs.gov/pub/irs-pdf/f1041sk1.pdf
Source: the IRS instructions for the beneficiary who receives Schedule K-1 (Form 1041), and the form’s own code list, read at irs.gov on September 29, 2026. General information, not tax advice. Your own facts decide the outcome, and a preparer, the estate’s or trust’s fiduciary or the IRS is the right place to confirm anything consequential.