AMT Adjustment Bug in 2023?

[AllanX]

I need to adjust stock basis for AMT as the stock was purchased multiple years ago as an ISO exercise.

From what I see and read online, the only way to do this is by lump sum adjustment of investment income in the "Let's adjust your investment income" page. The "gain" figures entered on that page however, do not seem to have any effect on Form 6251 line 1k. No matter what I do, that line always seems to be zero (so the AMT gain is exactly the same as the standard capital gain).

[AllanX]

(the original post should have referred to line 2k, not 1k)

I found the solution is to open form "Schedule D AMT" and manually edit Part II Column g (Gain or Loss Adjustment). In order to do this, you must choose to Override the values in that column (right click and choose "override").

[w15]

I have the same issue.
I followed your advice to override Schedule D AMT. 
However, my Form 6251 line K, still shows 0.
So, I don't know how to fix it.

Did you have to do anything else?

[ssfrancis]

I also believe that TurboTax has a bug -- or at least fails to guide the user to do this properly.  I do not believe that Schedule D AMT is the correct place to fix this.  With the same problem, I went to the Form 6251 Wkst in Forms mode and overrode the  line K1, subline 3 entries with the actual numbers that should be there.  The regular tax gain from my Schedule D entries, and the AMT loss from my own calculations ((FMV at exercise - sold price) * # of shares; 2 sale dates and 5 different strike prices; yuck).  This made a *substantial* difference in my tax outcome from what TurboTax was computing.  I was able to recover much of the AMT tax paid on the phantom gain in the year of exercise.  Note that in my case I also had substantial new phantom tax gains from the exercise of additional ISOs in 2023.

[taxsniper]

That would be nice, but the maximum capital loss you can use is $3,000, even for an AMT adjusted cost basis for the qualifying sale of stock from previously (prior years) exercised ISOs.

So even if you lost $100k in the sale, according to your AMT's cost basis (FMV at date of exercise), you AMT capital gain for this year is only -$3k.  So you won't recover much of your credit this way.

However, you've likely made large capital gains on the sale in your normal tax's cost basis (Strike price), so the difference between that and -3k will get you at least some of your AMT credit back.

[ssfrancis]

Perhaps you meant to say "the maximum capital loss you can use is $3,000 against ordinary income"?  I believe that you can use the AMT loss both to offset AMT (e.g. due to additional ISO exercises) and to offset regular tax capital gains (from selling the previously exercised stock) -- but I certainly agree that you can't offset more than $3,000 of ordinary income.