Employee A is hired January 2, 2001. During her first employment year which ends January 1, 2002, she works more than 1,000 and turns age 21.

Adoption agreement states "an employee will become a Participant on the Plan Entry Date immediately following or coincident with the date Employee completes the eligibility conditions."

If Entry Dates are January 1 and July 1, when does this employee enter the plan?

When did the Employee complete the eligibility conditions: January 1 or January 2?

Read the eligibility conditions more carefully. If the plan requires "one year of service" for participation, then her entry date is July 1. She hasn't completed a year of service at January 1.

With respect to the specific dates mentioned, there are many sponsors who make an administrative interpretation that the employee may enter on January 1 after hire, on the assumption that, since it is a (pretty much) universal holiday, NO employee can begin work on January 1.

If so, consistency of application is important.

Thus, the answer may not be found in the plan, or the SPD, but in that well-documented administrative manual maintained by the sponsor.