Normally, as per the existing Indian tax law, a person can file his ITR for one year only at any given point of time. However last date for filing of the ITR for financial year 2019-2019 which was 31-0-3-2020, has been extended from time to time and as of now it is 31st December, 2020 due to the Covid-19 pandemic. So as of now you can file ITR for financial year 2018-2019 as well as for 2019-2020 i.e. for assessment year 2019-2020 and 2020-2021. The due date for filing of the ITR for financial year 2019-2020 has also been extended till 31-12-2020. However you can file the ITR for Financial year 2019-2020 till 31-03-2021 with late fee as may be applicable. So as of today you can file your ITR for two financial years only and not beyond.

However, as per Circular 9/2015 [F.NO.312/22/2015-OT], Dated 9-6-2015, you are allowed file ITRs for past six years after following the procedure laid down in that circular provided you are entitled to claim any income tax refund or are entitled to carry forward any loss. So in case you are entitled to claim refund or have any loss to carry forward, you can avail this opportunity file old ITRs also.