GSTR 3B -doubt

Maya (Student) (658 Points)

20 September 2018  
Dear frds/ experts,
If a company, which is having T.O. less than 1.5 cr during previous year, have filed Gstr 3B for Apr & May 2018 monthly. Now my questions are,

1) Since it is having less than 1.5 cr during previous year, we can opt for quarterly filing. By analysing above said condition, shall we able to file returns for June month quarterly? If so it starts from Apr'18 to Jun'18. But for Apr & May'18, returns already filed. Now how to solve this problem?

Please treat very urgent...& hope u do needful at the earliest.