As long as you enable tax calculation and select AvaTax as the tax calculation method in your business application, AvaTax automatically calculates a sales or use tax rate on a variety of transaction types according to the taxability rules of those products (exempt customers aren't charged sales tax).
Use these optional fields in the Sales Transaction Entry dialog box in Microsoft Dynamics GP to customize how AvaTax calculates taxes.
Customer PO Number: On invoices and returns, enter a number here to trigger single-use exemption certificates you've configured.
Trade Discount: AvaTax allocates this discount to each line item in tax calculations.
Freight: AvaTax associates this item with the tax code/shipping code or default tax code you set in the AvaTax Configuration dialog box.
Miscellaneous: AvaTax recognizes this as a line item and can apply tax codes to it.