panalty on non payment of tax

Manohar Singh (288 Points)

17 October 2018  
Sir
I have already filed NIL gstr 1 and 3b for the month of August and september 2018.

but now I have got some invoices of sale and purchase of August 2018

and some invoices of sale in month of September 2018

1. can I claim itc of the invoices of August?
2. what panalty I have to pay on tax payable.?
3. can I revise filed gstr 1 and gstr 3b .before 20 October 2018.

Please guide me.
Thanking you