Short answer? Nothing!
Just keep using $upertill the way you have been. But, please take note that we will not be making any changes to the program to show the letters ‘HST’. Receipts and report will continue to show GST (and PST).
But, if we are required by law to do so, it will be done. In this event, everyone who wishes to upgrade can do so. There will be an upgrade fee (to be determined).