Oracle eBusiness Tax – where does the address for the Bill-To in Payables come from?

In Oracle Payables, we know the Ship From and the Bill From are the supplier(Vendor) address but where does the address come from for the Bill to? Not the Legal Entity as might be expected! It comes from the location address that is attached to the operating unit

Bill From – Supplier Address
Ship From – Supplier Address
Bill To – Location linked to the Legal Entity – this can be changed with the ‘Customer Tax Payer ID’
Ship to- Defaults from the supplier site but can be NULL

Interestingly, when you create an employee, there is no Bill From, Nor Ship From that the eBTax engine can use! So if your default  ‘place of supply’ rule is looking at the bill or ship from then you have to have a specific rule, for the event class of ‘expense reports’ to point the Place of Supply to the Bill To!