There are many taxpayers who were required to file the GSTR1 on a quarterly basis but by mistake while logging onto portal chose the option to file the monthly return. Now, such taxpayers are eagerly looking for the solution to this problem, but it is sad to know that as of now, there is no option to reverse this selection. So, if you have chosen to file the return monthly instead of quarterly, then you cannot opt out until the end of the financial year 2017-18. In the next financial year, you will be able to change the option.