Forget to take credit of an invoice in the month of March 2020

If you missed claiming Input Tax Credit (ITC) on an invoice for March 2020 when filing your GSTR 3B, you cannot revise the original return. However, you can claim this missed ITC in a subsequent GSTR 3B return. The credit can be claimed in the next available return, up until the due date for filing the September 2020 GSTR 3B or the annual return filing date for the 2019-20 financial year, whichever comes first.