There are two types of membership in an HOA: voluntary and mandatory. In a voluntary association, homeowners have the ability to opt in or out of membership. They can choose not to join the HOA and be exempt from the obligations that come with it. Of course, this would also mean that they would not receive the same benefits as members of the HOA. In mandatory associations, membership is compulsory. Homeowners who buy a house in the HOA community automatically become members of the association, with no way to opt out of it. Mandatory membership associations are the most prevalent, with voluntary associations being quite rare.