Dredging this back up (sorry) to think out loud. My AGI is over the limit to the new 22% bracket, but my taxable income post-deductions was under $32k last year, so well within the new 12% bracket. I certainly don't expect to move into a lower bracket in retirement, and I may move into a higher bracket, so I think the Roth still makes sense.
Now that I realized I'm supposed to establish my bracket using my taxable income, I also believe I'm in the 0% bracket for long-term taxable gains, with about $6k between me and the ceiling. In CA, taxable gains are counted as income, and I am also 2.5k shy of the next state bracket. Given that my gains from the last year is in the three digits, these seem like safe margins for the moment.
This makes me less anxious about my choice of what to buy in a brokerage account, because it doesn't look like I will have to pay capital gains tax on it no matter how tax-inefficient it is. This may not be a great strategy long-term, of course. In my Roth I'm in a target date index fund; any reason I shouldn't stick with this in a brokerage account? I will have enough to clear the minimum investment at my next paycheck in 2 weeks.
Also, this feels like a stupid question, but... should I be selling and re-buying each year (after the rollover to long-term) to realize my gains in the 0% bracket, so I will have less to realize when I (hopefully) move up a bracket post-grad school?
I suppose the downside there - assuming I'm not missing something obvious - is that I'm realizing the gains as income in California, a high-tax state I plan to move away from after graduating. If this is the only downside, the choice might require some actual math.