upto A.Y 2017-18 the return can be revised at any time before the expiry of one year from the end of relevant assessment year or before the assessment is made whichever is earlier. Thus return of A.Y 2018-19 can be revised till 31st March 2019 or before the completion of the assessment whichever is earlier and return relating to A.Y. 2017-18 can also be revised till 31.03.2019