Part III was added in order to track dependent coverage for self-insured plans. The instructions are specific: “Complete Part III ONLY if the employer offers employer-sponsored self-insured health coverage in which the employee enrolled. This part must be completed by an employer offering self-insured health coverage for any employee who enrolled in the coverage, regardless of whether the employee is a full-time employee.”
Unless the employer’s policy is self-insured, you will not put anything in Part III of Form 1095-C. A self-insured group health plan (or a “self-funded” plan, as it is also called) is one in which the employer assumes the financial risk for providing health care benefits to its employees. Self-insured employers pay for each out-of-pocket claim as those claims are incurred instead of paying a fixed premium to an insurance carrier – the arrangement known as a fully-insured plan. Even though these plans are called self-insured plans, an employer typically does not assume 100% of the risk for catastrophic claims. Rather, the employer buys a form of insurance known as stop-loss or excess-loss insurance to reimburse the employer for claims that exceed a predetermined level.