federal law that mandates you must buy insurance unless it is offered through your employer. law stipulates, among other things:
-no lifetime limits on benefits (e.g., you can't get cut off if you get really sick);
-no denials for pre-existing conditions;
-can stay on parents' insurance until 26 years old;
-appeals process for insurance coverage decisions, including an external review process (this is huge for anyone who has ever been denied coverage and can't really find out why);
-small businesses get tax credits for providing insurance;
I just don't receive full coverage from my company. A lot of companies are taking this route now.
You may find your company will either lower the number of employees to under 50, or reduce your number of hours of work to under 30 hours/week. This will relieve them of giving you any coverage at all, although you will still be liable for getting it and paying for it yourself under obamacare.