There is only a link to the business area if you have created one in Customizing of Financial Accounting (FI).

When creating/changing business entities, you may be required to enter the business area (required field) even although this field has been set as optional in Customizing.

In this case, the field status setting is overridden by the "Enable business area balance sheet" in FI. If this field is set in FI Customizing, the business area field has to be filled in for all FI postings.

For FI postings on Real Estate objects, the business area is derived from the business entity. Consequently it would not be possible to make automatic postings on Real Estate objects if the BE has no business area.

The field status control for the business area field on the business entity only has an effect when the business area balance sheet has been disabled in FI.