For anyone considering recognizing more gain or doing more Roth conversions this year, I ran across a couple of quirks in the way gains may be taxed.
Suppose you have short term gains (say, $3000) and long term losses (say -$1000), so that you're net positive (+$2,000 short term). Not a common situation, but here added long term gains can get taxed at short term (ordinary income rates).
In this example, if you generate an extra $500 in long term gains, that reduces the LT loss by $500, thus increasing the net short term
gains by $500: Net LT loss = $500, net gain (short term) = $3000 - $500 = $2500.
If your income is in the region where some but not all cap gains are taxed at 0%, then adding $1 of ordinary income can increase your taxes by 27¢, i.e. it's taxed at 27%. Kitces has an excellent piece on this; see examples 3 and 4.https://www.kitces.com/blog/long-term-capital-gains-bump-zone-higher-marginal-tax-rate-phase-in-0-rate/
He discusses how in this situation it is preferable to generate long term gains (even if taxed at 15%) as opposed to doing Roth conversions (even if nominally taxed at 12%). Going further, if one doesn't have much in cap gains/qualified divs, ISTM that it can still make sense to convert all the way up to the next tax bracket. A small amount will get taxed at 27%, but with little in cap gains, most will get taxed "normally". But if one has lots of cap gains that would get pushed into the 27% bracket, it pays to defer converting.
This suggests a multiyear strategy for planning periodic sales of assets and Roth conversions. It can be advantageous to lump them into alternating years. One year you take two year's worth of gains (taxed at 0% or 15%). The next year you work to minimize your cap gains (so there are few gains to get taxed at 27%) and convert more retirement money. Even if those conversions push you into the 22% bracket, that's still better than having a lot of cap gains taxed at 27%.
One needs to look at how much in gains one expects to recognize (including fund distributions), how much one wants to convert, other ordinary income, to see if this lumping strategy helps.