GSTR-1 filing deadline extension grants later dates for large taxpayers to furnish outward supplies details. Extends the due dates for furnishing details of outward supplies in FORM GSTR-1 for registered persons with aggregate turnover of more than 1.5 crore rupees in the preceding or current financial year, superseding an earlier notification, and specifies extended deadlines for July, 2017 to March, 2018 in a tabulated schedule; further extensions for furnishing details or returns under the provisions for inward supplies reporting and return filing will be notified later in the Official Gazette.