Updated October 18, 2026. Quick answer: Lines 2d to 2h each adjust one item from the regular tax to the AMT. Line 2d is the depletion difference, 2e and 2f deal with net operating loss deductions, 2g adds specified private activity bond interest, and 2h covers qualified small business stock. Each line has its own sign rule.
Line 2d: depletion
The caption is “Depletion (difference between regular tax and AMT)”. The instructions begin “Refigure your depletion deduction for the AMT.” On the limit: “Figure this limit separately for each property.” The entry rule is “Enter the difference between the regular tax and AMT deduction. If the AMT deduction is more than the regular tax deduction, enter the difference as a negative amount.”
Line 2e: net operating loss deduction
The form’s caption is “Net operating loss deduction from Schedule 1 (Form 1040), line 8a. Enter as a positive amount”. The instructions have no separate paragraph for line 2e, so the form’s own caption is the guide. Take the number from the Schedule 1 line the caption names and enter it as the caption says.
Line 2f: alternative tax net operating loss deduction
The caption is “Alternative tax net operating loss deduction”. The instructions define it: “The ATNOLD is the sum of the alternative tax net operating loss (ATNOL) carrybacks and carryforwards to the tax year subject to the limitation explained later.” They warn “Your ATNOLD may be limited.” The limitation steps are laid out in the instructions for line 2f, and they should be followed there rather than summarized. The entry rule is “Enter on line 2f the smaller of the ATNOLD or the ATNOLD limitation. Enter it as a negative amount.”
The instructions also say “The treatment of ATNOLs doesn’t affect your regular tax NOL.”
Line 2g: private activity bond interest
The caption is “Interest from specified private activity bonds exempt from the regular tax”. The instructions say “Enter on line 2g interest income from “specified private activity bonds” reduced (but not below zero) by any deduction that would have been allowable if the interest were includible in gross income for the regular tax.” On where to find the amount: “Each payer of this type of interest should send you a Form 1099-INT showing the amount of this interest in box 9.” For fund dividends: “This specified private activity bond interest dividends amount should be reported to you in box 13 of Form 1099-DIV.” The tax forms that report interest are covered at Form 1099-INT boxes 4 to 7.
Line 2h: qualified small business stock
The caption is “Qualified small business stock, see instructions”. The instructions say “If you claimed the exclusion under section 1202 for gain on qualified small business stock acquired before September 28, 2010, and held more than 5 years, multiply the excluded gain (as shown on Form 8949 in column (g)) by 7% (0.07). Enter the result on line 2h as a positive amount.” The exclusion itself is reported on Form 8949, which is explained at Form 8949 code Q.
Where the number comes from
Line 2d comes from refiguring your depletion, 2e from your Schedule 1, 2f from the carryovers you track for the AMT, 2g from your Forms 1099-INT and 1099-DIV, and 2h from the gain excluded on your Form 8949. The instructions remind you to “Keep records that show how you figured income, deductions, etc., for the AMT.”
Where it goes next
These lines flow into the line 4 total, where the form says “Combine lines 1b through 3.” The earlier lines are on the lines 2a to 2c page, and the stock option line is on the line 2i page.
Edition and line numbers
This page reads the 2025 Form 6251 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 6251 header says “Attach to Form 1040, 1040-SR, or 1040-NR.” 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 a depletion difference as positive when the AMT deduction is larger. The instructions say “If the AMT deduction is more than the regular tax deduction, enter the difference as a negative amount.”
- Entering the ATNOLD without its sign or limit. The instructions say “Enter it as a negative amount.”
- Entering the 1099-INT total on line 2g without reducing it. The instructions say “reduced (but not below zero) by any deduction that would have been allowable”
Related: Form 6251, Form 1099-INT boxes 4 to 7, Form 8949 code Q, Form 8949, and Form 6251 line 2i.
Sources
- Instructions for Form 6251, Alternative Minimum Tax, Individuals (2025): https://www.irs.gov/pub/irs-pdf/i6251.pdf
- Form 6251, Alternative Minimum Tax, Individuals (2025): https://www.irs.gov/pub/irs-pdf/f6251.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.