healthPlanId

This term is proposed for full integration into Schema.org, pending implementation feedback and adoption from applications and websites.

Thing > Property > healthPlanId

The 14-character, HIOS-generated Plan ID number. (Plan IDs must be unique, even across different markets.)
Values expected to be one of these types
Text
Used on these types
HealthInsurancePlan

Source

https://github.com/schemaorg/schemaorg/issues/1062