Doctrine of Partial Merger and Doctrine of Total Merger :

The second proviso in section 147, provides that the doctrine of partial merger shall apply to reopening in a case where an assessee has filed an appeal etc. for an assessment year. It has been provided that the Assessing Officer may assess or reassess such income, o ther than income which has been the subject matter of any appeal or reference or revision, which is chargeable to tax and has escaped assessment. The doctrine of partial merger also holds good for section 154 and section 263.

However, the concept of total merger would apply in the case of section 264. The Principal Commissioner or Commissioner of Income-tax has no power to revise any order under section 264, if the order has been made subject to an appeal to the Appellate Tribunal, even if the relief claimed in the revision is different from the relief claimed in the appeal and irrespective of the fact whether the appeal is by the assessee or by the Department as the concept of total/complete merger is applicable for section 264.