Is open enrollment permitted when a plan is restated? For example, a new plan may require one YOS and age 21 to participate, but waive these requirements for anyone employed on a certain date, say January 1. Can this also be done when a plan is restated? I was always under the impression that it could be done only for new plans. Thanks.

I believe open enrollment can be accomplished at any point via an amendment or restatement. Anyone disagree? Not sure on a code site for this.

Issue is that everyone then become eligible if the were employed on or before x date. Be careful - if your intention is just to have certain ee's come in, you may be surprised.

The amendment/restatement is usually used in M&A transactions. Easy way to make all the new ee's come into an existing plan.