Doctrine of merger depends on the issues actually decided, and limitation barred the later revision

Section 12(4)(b) limited the Board of Revenue's suo motu revisional power to the assessment order actually in issue before it. The Board could not treat the Deputy Commissioner's later revisional order as the operative order where the exemption point had never been raised in that revision. The doctrine of merger was not automatic or universal; it depended on the scope of the statutory revision and the subject-matter actually considered by the superior authority. Because the issue before the Board was distinct from the issue considered by the Deputy Commissioner, there was no merger of the assessment order into the revisional order, and the revision was time-barred.

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Issues: Whether the Board of Revenue could validly revise the assessment after four years by treating the earlier revisional order of the Deputy Commissioner as the operative order, and whether the doctrine of merger displaced the original assessment order for the purpose of limitation.

Analysis: The limitation in section 12(4)(b) applied to the Board of Revenue's suo motu revisional power in relation to the assessment order that was actually the subject-matter of its proceedings. The Board was examining the revised assessment order of the Deputy Commercial Tax Officer dated 28 November 1952, not the Deputy Commissioner's later revisional order, because the issue of exemption of the cotton purchase value had never been raised before the Deputy Commissioner. The doctrine of merger was held not to operate mechanically or universally; it depends on the scope of the statutory appeal or revision and the actual subject-matter dealt with by the superior authority. Since the point before the Board was distinct from the point considered by the Deputy Commissioner, there was no merger of the assessment order into the Deputy Commissioner's order.

Conclusion: The Board of Revenue's revision was barred by limitation under section 12(4)(b), the doctrine of merger did not apply, and the High Court's view that the assessment order could not be revised was correct.

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