Just go through your returns again sir the IT department might have failed to take any other loss or expenses reported by you, such as loss from house property or deductions under chapter VI A.
they wouldnt have taken the income directly at 17% of the turnover.
There might have been a possible mis placement of any items in the ITR.
kindly go through your ITR sir, you will find a possible error on both your side or in the IT Department.
because one of our client had same problem, when we verified the ITR we came to know that difference between our income and income assessed by IT department is due to failure of non inclusion of loss from house property.