The health insurance subscription is billed at cost (the actual premium charged by the insurer) plus a flat $15 administration fee per policy per month.
The administration fee covers the cost of managing the policy — including enrolment, dependent management, claims liaison, and renewals. It's a single fee per policy regardless of premium size or number of dependents on the policy.
If your employee has multiple dependents on a single policy, the fee is still $15 per policy.