Gst liability from august, date of certificate from septembr

This query is : Open

Querist : Anonymous

Querist : Anonymous (Querist)

20 September 2017 I am a trader in fabrics. Since, fabrics was a non taxable item I was not registered under any previous laws. From 01/07/2017 to 09/08/2017, I have sold goods of Rs. 20 lacs approx. On 09/08/2017, I have crossed the limit of Rs. 20 lacs and applied for registration under GST and while registering I selected the option 'Crossed the threshold limit' and entered the date of liability as 09/08/2017. I received the GST certficate on 02/09/2017. The date of liability is also mentioned in the GST certificate correctly as 09/08/2017. But while filing GSTR-3B for the month of August, in return dashboard the option to select the month of August is not available. The month starts from September.

I have already raised the bill adding GST and quoting ARN number and have already issued revised tax invoice with GSTIN according to the GST rules. How do I file 3B now and GSTR-1 later on so that my buyers will get credit of it?