Change of bill date in gstr1

From the above query, it can be seen you have wrongly mentioned the invoice of FY 2020-21 as invoices for FY 2019-20. 

There is no such mechanism now to correct the dates of the invoices because the last date to make such rectification for FY 2019-20 was September 2020 and for FY 2020-21 was September 2020. Both the dates have passed. 

The recipient can claim the ITC but there will be a mismatch of ITC as compared to GSTR 2A and GSTR 2B. 

There is a time limit on availment of ITC and not utilisation of ITC. ITC unutilised can be carried forward for n number of years.