We are having the same problem with "based on location".  Almost 50% of the time Quickbooks Online does not choose the correct tax rate for a customer's address.  We have to constantly override the tax amount it chooses and put in the correct one that we get from the state Address SalesTax Look Up Directory.  Then every time you edit an Estimate or Invoice, Quickbooks instantly switches it back to the incorrect amount.  So frustrating and time consuming!  Any suggestions?