Provision sores and Super Market B2B & B2C Sales.

HSN details mandatory in gstr-1

1) If your aggregate turn over in the preceding financial year is more than 5 crore then in both the case you have to mention 6 digits HSN code compulsary in GSTR1
2) If your turn over in the preceding financial year is less than 5 crore then you have to mention 4 digits HSN code of B2B is compulsary ,and for B2C transactions it's optional or not necessary if your aggregate turn over in the previous financial year is less than 5 core .

Please refer Notification 78/2020  dated  15/10/2020  for my above reply . 

Agree with prasad ji.
As mentioned Notification 78 do prescribe HSN code to be mentioned in GSTR 1 but it mandates the HSN need to be mentioned in Tax Invoice.
So if your AT is > 5 crore , need to mention 6 digit HSN in Tax Invoice
& if it is below 5 crore then 4digit HSN need to be mentioned on tax invoice only for the supply made to B2B.

As in notification only prescribed the HSN to be mentioned in TAX INVOICE.
But as in GSTR 1 the values & other field are captured from Tax Invoice & if you are not required to mention HSN for B2C invoice then , only B2B invoices HSN need to be reported in table 12 of GSTR 1.