Unable to file return

In the event of any errors or omissions in the tax returns, the return may be revised within the specified timelines. For FY 2016-17, the due date for revision is within two years from the end of the financial year, whereas for FY 2017-18 onwards, this period has been curtailed to one year from the end of the financial year. However, the tax returns in either case need to be revised before the completion of assessment.

So I think u cant file a belated return for FT 16-17 now as it could have been filed only till 31.03.2018.