Pretty sure I am right on this, but am having a hard time finding chapter and verse on it:

The 5-year contribution rule on Roth IRAs does not take into account how long ago your Roth 401k was first opened.

In other words, if you started funding your Roth 401k 12 years ago, and then rolled it to your first Roth IRA ever, your 5-year contribution clock starts on the day the rollover is completed. The fact that you first funded the Roth 401k 12 years ago does not count toward the 5-year contribution clock.

But I am wondering, where is this spelled out in writing? Is it “spelled out” by omission, in that the code doesn’t make any mention of factoring in your Roth 401k participation time with regard to the Roth IRA 5-year rule, or is there a reg Q&A that specifically states “it doesn’t count”?