Correction Return Of GSTR1

Somen Dutta (Asst. Accountant) (43 Points)

08 September 2018  
we are filed gstr1 for the month of july'17 but there are considered some bill with wrong invoic date as 31/07/17 which actual invoice date is 1/8/17.

now we want to submit correction return for the month of july'17 and aug'17.

my question is ----
1) it is mandatory to filed correction return when no annual tax difference with the accounts, there are just a technical mistake ?

2) when it is mandatory to filed correction , what is the right procedure?

kindly help me pls to solve the problem.