If there is an apparent mistake in your tax return, a rectification under section 154(1) can be done. Read here in detail about rectification under section 154(1).
Sometimes assessing officers pass rectification orders online without giving a copy to the taxpayer. In such situations the taxpayers were devoid of a copy of the order and could not appeal or review the rectification.
CBDT has released a circular directing all assessing officer to pass the rectification order in writing. And this must be duly provided to the taxpayer.
As per CBDT release (F.No.225/305/2015-ITA.II) dated 15th February 2016