This doesn't work if you have someone that uses QBO along side an integration. This caused issues with our previous PSA when this setting kept getting enabled and we had transactions numbers stepping on one another. We switched to HaloPSA and it submits the invoice to QBO, QBO sends back the tax and the invoice number. It works well if QBO isn't broken. This has been going on for 6+ months and they are/will be forcing users to the new invoice interface with no way to turn it off.