You posted on a thread that was originally asking about an annuity with a rider. If the annuity has no actuarial value beyond the accumulation value, the year-end accumulation value would be the amount on which to base the RMD. For more details, see CFR 1.401(a)(9)-6 Q&A-12:
https://www.ecfr.gov/current/title-26/chapter-I/subchapter-A/part-1/subject-group-ECFR6f8c3724b50e44...
(The older Cornell URL is currently unavailable.)
