Options for correction of mistakes in past income tax returns

livemint.com:

The time limits have, however, been shortened over the past few years, and currently for a tax return due for the financial year 2022-23, which would have been filed by 31 July 2023, you could have filed a revised return only till 31 December 2023. Any mistakes that you discover after 31 December 2023 cannot be rectified by filing a revised tax return as a matter of course. The problem really is that most taxpayers discover the mistakes in their tax returns only when they are filing their tax returns for the subsequent year.

By then, it is too late to file a revised tax return. If the mistake is such that you have undercomputed your tax liability, you do have an option of filing an “updated tax return", which is different from a revised tax return. An updated tax return however attracts an additional tax of 25% of the differential tax if the updated tax return is filed within 2 years from the end of the financial year, or 50% of the differential tax if it is filed within 3 years from the end of the financial year to which it relates.

You cannot file an updated tax return after more than 3 years. Besides, there are various limitations in filing an updated tax return. There has to be an additional tax payable—you cannot file an updated tax return to claim a lower income or claim TDS (tax deducted at source, not claimed in the original return, which would result in a tax refund.