Optimization overload: Roth Conversions, ACA (PTC/CSR), Taxable, 457b, Child Tax Credits, ABLE, FAFSA, 529s, Mortgage.

I've been trying to make sense of our base RE scenario, and it's a lot.

Here's what I'm trying to figure out. I considered writing a simulation to help find the best plan, but I doubt I'll have time this year in order to do conversions or make other changes.

1. Should I consider Roth conversions in the 22 percent bracket now?
2. When should I use the 457b?
3. Should we be maxing all of this traditional space? (There's a 401a that's mandatory; but 457b/401k are optional or could be Roth.) Assume that we're spending what's not getting contributed below, so conversions and Roth taxes would be paid for from taxable.
4. For ACA, it seems like we'd need to cycle 399 and <200 FPL years or do some pre-RE conversions. Any other option?
5. Have you done analyses that helped you figure out a priority order or something else that might help me narrow down how many moving parts I have?

Here's our overall setup:

• Year: 2027 (midyear)
• Age: 47 (then)
• 59.5: late 2039
• Child tax credits: 2x to 2036, 1x to 2038
• FAFSA: 1x 2036-2037, 2x 2038-2039
• 529s: 120 percent of present value of CoA.
• ABLE account: likely 1 or 2 (TBD; not yet opened)
• Mortgage: 22k year (P&I); 400k balance
• Taxable: 325k (50k in LTCG)
• Roth: 35k in contributions/conversions (half available now; half in 5-year rules)
• 457b: 210k (~50k more in contributions)
• post-59.5 (traditional): More than needed. Can easily convert 300k and still stay at high probability of 96k expenses (ex-P&I) being fine. (~70k more in non-457b contributions)
• Expense target (ex-housing P&I): 72k

One option we considered is having one of us work part time in a role that would get benefits, defer almost all the comp into a retirement account, and convert up to the top of the 12 percent bracket. That's about an 118k conversion (10k for taxable interest/dividends) for about 6.5k in federal tax. Good deal, but requires work.

I saw this recently, too: https://www.reddit.com/r/financialindependence/comments/1ojmx5d/balancing_aca_subsidy_taxes_and_roth_conversions/