A homeowners association (HOA) or property owners association (POA) is in USA an organization created to maintain the appearance and common property of a group of houses, typically a subdivision or neighborhood.
There is no agreed upon tagging scheme for HOAs, particularly in regards to subdivisions within an HOA.
One possible method is to tag the boundary of the HOA as boundary=administrative, with admin_level=10, or whatever is appropriate for the local area. Some HOAs are further divided into neighborhoods, and neighborhoods divided into clusters. Increase the admin_level for each successive level.