Default tax code in iExpenses based on expense location

Hi

We want to populate the tax code in iExpenses lines based on the 'Expense Location' field that is populated by the user (or defaulted from a credit card transaction).

Has anyone else done the same?  I've researched geographical tax rules, but as the supplier is the employee (in Australia), we want to use the tax code of the expense location, hence a 'ship to' location type rule would not work.

We currently default the tax code from the expense type in the template.

Any thoughts or insights would be appreciated.

Cathy.