How is the Tax code derived in AutoInvoice?

AutoInvoice first looks at the transaction type setup (Menu: Setup>Transactions>Transaction Types) and the TAX_EXEMPT_FLAG column in RA_INTERFACE_LINES_ALL. If the 'Calculate Tax' box is checked on the transaction type OR the TAX_EXEMPT_FLAG column is 'R'(for Required), it tries to derive the Tax code.

To get the tax code, AutoInvoice looks at the following places in the following order, stopping at the first place where it finds a tax code:
- Ship-to site
- Bill-to site
- Customer
- Item