Universal Availability

[JRN]

Can a 403(b) Plan impose a minimum age and/or service condition for eligibility to make salary deferral contributions without running afoul of the universal availability rule? For example, could the Plan provide that an eligible employee must complete a short probationary period of employment, such as 30 days, before becoming eligible to make salary deferral contributions to the plan? And, can a 403(b) Plan provide for entry dates, such as the first day of the next calendar month or first day of next calendar quarter without violating universal availability, or must otherwise eligible employees be permitted to commence salary deferral contributions immediately on their date of hire?

Are these types of administrative provisions permissible? Thanks.