One of my friend is running a Proprietory concern and his annual turnover for the year 2017 -18 ( Jul 17 to Mar 18 ) was less than Rs. 1 crore. As such, he says, he has not filed the GSTR 9 - annual return, since it is optional to file annual return, if the annual turnover is less than Rs. 1.50 crores for the FY 2017 - 18. Is there any such option? Kindly let me know the section under which such option has been granted. If not, what is the corrective measure for him ?