Penalty

Late fee for Nil Return - Rs. 20/day (CGST Rs 10 & SGST Rs 10)
Other than Nil return - Rs. 50/day (CGST Rs 25 & SGST Rs 25).
Maximum late fee Rs 10000 /month.

Also pay 18% per Annum interest for late payment for all outstanding payments. 

Late fee is auto calculated by gst portal while submitting returns.

Note: interest is not applicable for nil return filing.

50 per day (cgst-25&sgst-25)
max up to 10,000(5,000 each of cgst and sgst)

along with intrest 18% intrest

(non filing of return (nil return) what is the interest?)

If nil return then Interest not levied...

Late Fee is applicable only Rs 20 (CGST Rs 10 & SGST Rs 10) for Nil Return...

Yes Agree with Raja ji , interest is not applicable on Late filing of Returns.

How much the amount of penalty for non filing of GSTR 1 ?