02 November 2017
Dear Sarath,
GSTR 1 once filed cannot be revised. Any mistake made in the return can be revised in the next months return. It means that if a mistake is made in September GSTR 1, rectification for the same can be made in October’s GSTR 1.
03 November 2017
Yes, you can't make amendments in GSTR 1, for any changes you can amend the same only in the next month's return, i.e. probably after 11/12/2017.