IDEA: Out of courtesy, call your new customer and ask for a sales tax exempt certificate BEFORE you bill them their first invoice incorrectly.

All companies have to comply with sales tax laws and are to bill the appropriate sales tax (appropriate rate for the county where delivery was made or where the sale occurred).  Unless the customer provides a sales tax exemption certificate (giving you authority not to bill them sales tax taking your firm off the hook in an audit)  you must bill the sales tax, then paid at the end of the month or quarter, send in the money to the state treasurer’s office.   Out of courtesy before this all occurs, if you did not receive a tax exemption certificate with the initial purchase order, call them to ask for it now that the sale has happened before you prepare the invoice.  Tell them you thought they may be tax exempt but wanted to make sure and give them an opportunity to correct the first invoice.   Tell them to please forward their exemption certificate for the delivery state and you will be glad to make sure not to add sales tax to their invoice.