For the financial year 2017-18, filing the GSTR9 annual return is mandatory if your business turnover exceeded ₹2 Crore. If your turnover was less than ₹2 Crore, filing is optional. This clarification is based on Notification 47/2019 CT, which specifies the ₹2 Crore threshold for both FY 2017-18 and FY 2018-19.
If turnover more than 2 Crore than it's mandatory to file GSTR 9 ANNUAL return for F.Y 2017-18 and F.Y 2018-19. if less than 2 Crore than it's OPTIONAL