Spousal Beneficiary RMD- adjustment for new tables?

Question is relating to a defined contribution plan.  Have a client who passed away in 2018, after his required beginning date.  He had a spousal beneficiary who has dutifully been taking RMDs since his passing.  Plan Document states that we established her annuity factor in the year that he died, then we reduce the factor by 1 every year moving forward.

Question that I can't seem to find an answer to is if and/or how the new life expectancy tables will affect her.  On the current tables, her annuity factor at age 60 (when he passed) would be 27.1, but on the old table which the RMDs have been calculated previously, it was 25.2.  Do we just continue subtracting 1 from 25.2 for every year that passed, or can we use the new tables, and subtract 1 from 27.1 for each year that has passed, and calculate based on that?  Basically, am I going to use 21.2 or 23.1 as my factor for 2022 RMD?

Any citations of code would be greatly appreciated, and I looked through Pubs 560 and 575, and can't find an explicit answer.  Haven't checked 1-401(a)(9) yet, as I assumed guidance would be forthcoming.

PMZJohn, there is a transition rule where you have been using the life expectancy of the beneficiary minus 1 each and now the table has changed. Basically, you go back and start with what would have been the beneficiary's life expectancy in the first year that he or she received a distribution, using the new table, and then subtract 1 from that for every year, including the pre-2022 years. So in your example, it would be 23.1. See Treas. Reg. 1.401(a)(9)-9(f).

But this only applies where you have a nonspouse beneficiary, or the surviving spouse was older than the participant. Otherwise you should be recalculating the surviving spouse's life expectancy each year. See Treas. Reg. 1.401(a)(9)-5, Q&A-5(c)(2).