What’s the difference between fully insured and self-funded health plans?

In a fully insured plan the employer pays premiums and the insurance carrier bears the claims risk. In a self-funded plan the employer pays claims directly (usually with stop-loss protection and a third-party administrator), taking on more risk in exchange for cash-flow control, claims data, and ERISA preemption of many state insurance mandates.

Why would an employer choose to self-fund?

Employers self-fund to gain control: access to their own claims data, ERISA preemption of state mandates and premium taxes, cash-flow advantages, the ability to keep savings in a good year, and freedom to customize the plan and its cost-containment strategies. The trade-off is taking on claims risk.