In cases where proof of health insurance coverage is required, an active member ID card can typically suffice as proof. In the event that a physical member ID card is not available (the carrier does not provide physical cards or the employee has not received the ID cards yet) a certificate of coverage can suffice as proof of insurance coverage.
A certificate of coverage is an official document from a carrier stating an employee is active in the group policy. If you want to obtain a certificate of coverage, you should reach out directly to your carrier.