It's highly possible that you could have made a mistake while filing your Income Tax Returns. You can revise your Income Tax Return before the assessment is made and provided you have filed your returns before the due date.
It's extremely important to remember that if you have filed your returns wrongly there can be serious consequences including imprisonment. It's best to revise your return if you have understated your income.
You can revise your income tax returns within one year from the end of the assessment year or before the assessment is made.
For example, for the the financial year 2013-14 you can file a revised before March 31, 2016. It's important to remember that once the assessing officer assesses your income you cannot file a revised income tax return.
Also, revision must be made with a good intention. It cannot be made for concealing a fact, or a deliberate omission.
Once you revise your returns, remember that the original stands withdrawn. If the IT department is of the view, that the omission made in the original return was intentional, the assessee could be penalised for the act.
Also remember, belated returns cannot be revised. This means that if the due date to file returns is July 31, and you have filed your returns after that date, you cannot revise your returns.
If you have concealed income for some reason, chances are that you could end-up paying penalty almost three times the amount due.
If you have revised your Income Tax Return there is a possibility that the same could come under greater scrutiny by the Income Tax Authorities. It's best to therefore avoid making a mistake in the very first instance.
In most cases if the assesse has revised his return to show a higher income, then there would be no penalty that is levied.