The earnings rolled over from the Roth solo 401k, along with any earnings accumulated after the rollover are subject to tax if you take a distribution until the Roth IRA is at least five years old. This means the rolled over money takes on the 5-year clock of the Roth IRA.
If your Roth solo 401k account is at least five years old when you roll it over to the Roth IRA, only the earnings accumulated after the rollover are subject to tax if distributed prior the Roth IRA being at least five years old. The earnings from the Roth solo 401k that are rolled over to the Roth IRA retain their original clock.
In all qualified distributions, not only must the account be at least 5 years old, you must also meet the age 59 ½, or death, or disability rule.
