This is from Avik Roy:
The law requires that every employer with 50 or more “full-time employees” offer “minimum essential coverage” in an “affordable” manner…
The penalty is triggered if at least one employee seeks federal exchange subsidies instead of gaining insurance form his employer. In that case, the employer will have to pay a non-tax-deductible fine of the lesser of $2,000 times the number of full-time employees ― 30.
If the employer does offer a health plan, but it isn’t “affordable” to all workers or fails to meet the “minimum essential coverage” requirements, then the employer pays the lesser of the fine described above, or $3,000 times the number of full-time employees receiving exchange subsidies.
What does this mean in reality? It means that employers have an incentive to offer coverage that is either “unaffordable” according to ObamaCare or that fails to meet the law’s “minimum essential requirements.” That way, the employer pays a penalty only for those workers who gain subsidized coverage on the exchanges. So the best way for employers to “dump” coverage onto the exchanges is not by offering no coverage at all, but by offering coverage that doesn’t meet ObamaCare’s requirements.