sec 139(5)

No specific consequences......... unless the changes are abnormal.......

It is proposed to substitute sub-section (5) of section 139 so as to provide that if any person, having furnished a return under sub-section (1) or under sub-section (4), or in a return furnished in response to notice issued under sub-section (1) of section 142, discovers any omission or any wrong statement therein, he may furnish a revised return at any time before the expiry of one year from the end of the relevant assessment year or before the completion of the assessment, whichever is earlier.

So for Ay 2017-18 can be revised u/s 139(5) till 31 march 2019.

What exactly is "compeletion of assesment" 

Completion of assessment......... means scrutiny assessment u/s. 143(3), or u/s. 144 but not u/s. 143(1).......

Ok Thanks Rambhia Sir.

Most Welcome.......