This field on the Misc tab of Customer Maintenance is for Tax Plan users. Use this field to indicate a tax plan associated with a customer. Click the down arrow (to the right of the field) to display a list of existing tax plans. Select the code that applies to this customer.
You can also click the Tax Override Plan hyperlink (in blue underlined text) to display the "Tax Plan" viewer, which is where you set up and view tax plans.
You must attach a tax exempt plan with all items that are never taxable for this customer if the customer is purchasing in multiple states.