The Goods and Services Tax (GST), which was introduced in April 2015 was replaced by the Sales and Service Tax in September 2018.
While waiting for the new SST bill to be passed, GST was zero rated from June 2018 to August 2018. This was a period of transition from GST to SST.
Registered businesses would first have to charge GST at 0% until August, then switch over to SST from 1st September.
For Sage 300 users, you would first need to set the GST tax rate to 0% and use that from June to August. At the same time, you would also need to setup SST in preparation for it’s introduction in September.
To setup GST at 0%, please see Setting GST to 0% in Sage 300.
Keep in mind that businesses are required to retain GST records for at least 7 years.