Under 105(h) nondiscrimination test as to benefits, is a requirement that some employees pay a higher premium than other employees (newly acquired sub paying full cost, while current participants cost is subsidized) discriminatory?

Did you ever determine the answer to this?

I ask because I am currently looking for IRS guidance about the point at which a self-insured plan becomes discriminatory when highly compensated employees make a lower contribution than do other employees. Did your research turn up any formula or other implementation material on that?

Yes, I believe you do have a discrimination problem if highly compensated individuals are paying less. See in general Reg. Sec 1.105-11©(3). It is possible that you could break the plan into 2 (one for each contribution rate) and if each satisfies the coverage requirements you would be ok.

Variations in self-insured medical plan premiums
I have been asked whether it is lawful for a self-insured medical plan to charge different premiums to employees on the basis of their incomes: the higher the income, the higher their premiums. It seems to me that nothing prohibits this practice as it discriminates against the highly compensated employees. Any thoughts?

Linda, I agree that should be okay under 105(h). It raises an issue in my mind if you allow employees to pre-tax the premium under Sec. 125 since highly compensated are getting a greater deferral, but it may be okay there too. Just a thought.