Applicability of interest on gst late payment

I have not filed gst returns from august 2017. Currently my GSTN has been cancelled. CTO has informed me to pay tax and file the returns and apply for revocation.

When i logged in due date is shown as 31st march 2019 for all the returns (GSTR-3B & GSTR-1).

Is interest to be calculated and paid for all the returns because i am of the opinion that interest should be calculated from due date and due date is march 2019 so no need to pay interest.

please advice me on the same