GST vide Notification Nos. 54/2020 dated 24th June, 2020, it has been issued that for tax payers having turnover upto Rs. 5 crores based on their principal place of business due date for filing of form GSTR-3B has been extended to October 1, 2020 and October 3, 2020 respectively(basis for Principle place of business is in the original notification accessed through link).
https://www.cbic.gov.in/resources//htdocs-cbec/gst/notfctn-54-central-tax-english-2020.pdf