Legal Associations is a set of components that aims to provide a centralized repository and a common mechanism for maintaining associations between business entities (non-legal constructs) and legal constructs (legal entities, establishments) and between just legal constructs. You can also use Legal Associations to maintain associations between balancing segment values and establishments for some countries.
When dealing with associations with establishments, these components are integrated into the Establishment Details page so that you can create associations between various attributes (such as Operating Unit/ Inventory Organization /Inventory Location / Ship-to and Bill-to Location) to establishments. These associations are mainly used by e-Business Tax as a component for tax calculations.
Associations are based on seeded cardinality rules, so it is possible to associate the same operating unit, inventory organization, and location to different establishments, even if they belong to different legal entities.
E-Business Tax needs the establishment information to determine what the imposed tax will be based on information present at the time of entry/creation of the transaction. Determining the establishment is necessary as it is the connecting entity that would determine tax registration and the other relevant details to determine tax.