Underreported GSTR1

Shubham (Practice) (869 Points)

17 March 2021  
Dear professionals,

I have missed including certain B2C sales of a client in GSTR1.
The GSTR 3B is still pending.

What would be the appropriate remedy?

1. Include the sale in relevant month's 3B and next month's R1.

2. Include in R1 and 3B of the next month and pay interest accordingly.