Common Mistakes while filing ITR
1) Always write down your userID and password in your diary. You can't burden yourself trying to remember the userID and password the next year. You won't remember. Check the case sensitiveness of the password. Also don't forget to write the question/answer.
2) Double check your email address in the ITR. Most people want to complete the first page of the ITR in a hurry, and later forced to file a revised ITR only to correct email address or date of birth or PAN number or even address. Go slow and do it thoroughly.
3) It is good to take a print of form 26AS. It better to fill ITR form by reading from a piece of paper than pressing alt+tab to view the other window in your computer.
4) In case your CA or TRP is filing returns on your behalf, ask them the userID and password for your records. If you want to view some tax details on your own, you can do so instead of running after them.
5) Make a separate file and store all documents related to your ITR. It pays to be systematic.
6) And last but not the least, if any doubt, log on to www.caclubindia.com lolllll.......
Others are welcomed to add some more points hereunder:-