(a) in an appeal against an order of assessment, he may confirm, reduce, enhance or annul the assessment; or he may set aside the assessment and refer the case back to the 5[ Assessing] Officer for making a fresh assessment in accordance with the directions given by the 6[ Deputy Commissioner (Appeals)] 7[ or, as the case may be, the Commissioner (Appeals)] and after making such further inquiry as may be necessary, and the 8[ Assessing] Officer shall thereupon proceed to make such fresh assessment and determine, where necessary, the amount of tax payable on the basis of such fresh assessment;