As part of the insurance market reforms enacted under the ACA, large employers are required to maintain a certain level of health insurance for their common law employees (and only their common law employees) or pay a penalty — the so-called pay or play or employer shared responsibility rules. The rules for determining which workers should, or even can, be offered coverage are quite daunting. This article provides a road map for determining which workers must have an offer of health insurance coverage from the employer to avoid triggering penalties under the employer shared responsibility requirements.