waiting periods for eligibility in self-funded health plan

[jeanine]

May a self-funded health plan impose different waiting periods for eligibility between salary and hourly employees? I would appreciate a cite to back up any opinions. I thought that as long as you treated similarly situated individuals the same it was OK. However, an earlier post to this board (2or 3 years back) indicated that the IRS had issued a determination letter saying this was discriminatory in a self-funded plan.