law: Expenditure-Tax Act, 1987 
  10. Best judgment assessment 
  If- 
  (a) any person fails to make the return
  
  required by any notice given under sub-section (2) of section 8 and has not
  
  made a return or a revised return under sub-section (3) of that section, or
  (b) any person having made a return fails to
  
  comply with all the terms of a notice issued under sub-section (1) of section
  
  9, or
  (c) the 16[Assessing] Officer is
  
  not satisfied with the correctness or the completeness of the accounts of the
  
  assessee, the 16[Assessing] Officer, after taking into account all
  
  the relevant material which he has gathered, shall, by an order in writing,
  
  make the assessment of the chargeable expenditure to the best of his judgment
  
  and determine the sum payable by the assessee or refundable to the assessee on
  
  the basis of such assessment.