Missed Sale Bill in GSTR1

You can file details of same bill in GSTR 1 of May month, Means disclose/include that bill in GSTR 1 of May, 2020.

Here u can do amendment of the bill which you have missed

The invoices which you missed out in current GSTR 1, need to be considered in your upcoming filing of GSTR 1

@ Ramya Bhat ji

Bill is missed / totally not entered in GSTR 1
than we have to add that invoice in as normal as in outward supply.

Amendments is applicable when we added bill but there is any wrong details entered, which we want to rectify in next GSTR 1.

Sagarji I will add sale bill in May GSTR1 but when my purchaser will get ITC in April or in May

Purchaser will get ITC in April month itself,
because date of invoice is of April which you are filing in GSTR of May 2020.

No issues. You can upload the bill while filing GSTR-1 of the current month. Since you have already shown the bill in GSTR-3B, there is no need to pay any interest/penalty/any other liability