I had always understood that employers could not require you to participate in a contributory plan, but I have to confess that I cannot provide you with any law that says so. Will your employer allow you to opt out if you can provide proof of other coverage? That would definitely hold water legally if they will.
I agree. Good question by poster. My response is experience based and not based upon any actual regs I can find either. But, my thoughts on this are that there simply is not any reg or law to prohibit nor allow opting out of either a contributory or non-contributory health plan. I think this is determined by the insurer / employer contract (employer only if self-insured). The basis being avoidance of becoming at cross purposes with other regulated areas such as adverse selection.
For practical purposes this would occur most often if one has another preferable health plan available. In that event my experience tells me that manay insurers would allow opt out of a non-contributory plan upon proof of other health insurance (OHI). Reason being although the percentage of participation is very high for a non-contributory plan, OHI available is not likely considered a "decline".
For a contributory plan the percentage of participation is usually much lower than for a non-. Therefore it is quite likely the employer/insurer contract will allow for opt out. BUT, for anyone considering this please be aware that health plans are often wise to opt outs and will reduce benefits for a dependent spouse that has employer group plan available. IE, be sure that the plan you wish to be a dependent on does not reduce benefits below the level available with your own employer plan.
Best to you, lkc15507
PS For those looking to opt out of a Non contributory plan, Section 125 does not require the employer to otherwise compensate for the opt out. Also the above answer is based upon status prior to full implementation of PPACA. As PPACA regs are still being interpreted and written there is no telling how the above will change with its full implementation.