California’s minimum participation requirement for non-contributory group health plans is

A 50% participation requirement would allow a significant number of eligible employees to opt out of the health plan, potentially destabilizing the risk pool. Such a low threshold does not align with California's regulations for non-contributory plans, which necessitate full participation to ensure collective risk management.

A 75% participation requirement still permits a considerable fraction of eligible employees to decline coverage. This percentage does not meet the state's stringent criteria for non-contributory plans, which mandate universal participation to maintain the integrity and sustainability of the health plan.

While a 90% participation rate reflects a high level of engagement, it still allows for 10% of eligible employees to opt out. California’s regulations explicitly require 100% participation for non-contributory group health plans, making 90% insufficient to meet legal standards.