What is Actual due date for GSTR 3B March 20 ?

Due date of return is remain same and thare is no change in due date but if you file return before 3rd july 2020 than interest and late fees are waived. Hence you can file up to 3rd july 2020 with interest and late fees.

As per Notification 32/2020 CT , Taxpayer having an aggregate turnover upto 1.5 crore can file GSTR 3B by 3/7/2020 without late fee & Interest.

The interest @ 9% applicable only on taxpayer whose turnover is more than 5crore & that to be Nil for first 15 days from due date.
For Eg .
For month March 2020 the due date is 20/4/2020 & Taxpayer file the same on 7/5/2020 , Number days of delay will 16 days (for calculating interest ) Hence Zero interest for 15 days + Interest rate @ 9% p.a for 1 day (16-15=1).

Thank you so much for clearing my doubt , @ pankaj sir @ Rajkumar Sir

Is there any late fee for the month of feb in gst 3b