About missing purchase

Now you have to make entry in your books then only you can show those invoices in your GSTR 1

But gstr 1 we show our sale

You can show/enter the missed purchase in its original date of invoice in books of accounts.

In dec18 GSTR3B, you add the missed ITC with. dec18 and file it.

Sorry guys, After make purchase entry in back date then you can show those invoices in your GSTR3B.

Agree With Mr. Vinod Sir 

Advice

Do not worry , Dept makes ITC available upto 31st March, If u want to clear your backlog

take itc in current 3b   

ITC can be claimed only within one year from the date of issue of tax invoice relating to supply. In any other case, the last date to claim ITC is earlier of the two below:

Before the filing of valid return for the month of September following the end of FY to which such invoice is related, or Before the filing of the annual return