The revision has to be done before the end of the financial year for which return was filed, i.e., 31st March 2019 for AY2018-19.
How you can revise your ITR
The process is quite similar to the one used to file an original ITR. It can be done through both online and physical mode. Here's a step-step guide to file a revised ITR online:
Step 1: Visit www.incometaxindiaefiling.gov.in
Step 2: Login with your credentials
Select 'Income Tax
Return' under the e-File tab
Step 4: Next, select the assessment year, ITR form name and the submission mode. Select relevant options in 'Field/Schedule' and 'verify your income tax'
Fill the asked details in 'Part A General Information' and select the 'Revised' option when asked 'Whether original or revised return?'
Mention asked details in all the tabs along with the ones you had missed earlier or had entered wrong information.
Step 7: Click on ‘Preview & Submit’
Step 8: E-verify your revised return
Although there is no restriction on the number of times a return can be revised, multiple revisions may attract the attention of the income tax authorities.