Thank you for taking the time to provide such a detailed response, @dmertz !
Your assumption is correct, that all the excess contribution is in the after-tax contributions. I calculate that I have over-contributed by $10420. $5000 in the 401a account, and the remainder in the Roth IRA. Some of the money is sitting in this default money market account, and it gains a minuscule amount each month by default, so even during the rollover, $5000 accumulates a few dollars that get taxed (per Fidelity). When I spoke to Fidelity, they said they do not check for any after-tax contributions in excess.
Since my last paycheck occurs at the beginning of December, I think I will speak with Fidelity to take care of this excess contribution return in mid-December. It sounds more simple to keep it all in one year, rather than having to do some stuff on 2022 return, and then the credit of tax withholding on 2023 returns. That sounds like I would have to remember to put in TurboTax 2023 somewhere.
