3792 / Can a plan restrict the types of 401(k) contributions that can be converted to a Roth 401(k)?

Yes. A plan that adopts an amendment permitting in-plan rollovers from traditional 401(k) accounts to Roth 401(k) accounts can, subject to otherwise applicable nondiscrimination requirements, restrict the types of contributions that can be rolled over. Further, the plan amendment can limit the frequency of these rollovers.¹

For example, otherwise nondistributable amounts may be permissibly rolled over, it is up to the plan itself to determine whether it will allow these rollovers. For administrative convenience, a plan may provide that it will only permit rollovers of otherwise distributable amounts or that nondistributable amounts can only be rolled over at certain intervals.