Prospective operation of tax amendments prevents reopening of final assessments unless retrospectivity is clearly expressed.

An amendment enlarging the period for revising escaped assessments is presumed prospective and will not reopen assessments that had already become final unless retrospectivity is expressed clearly or arises by necessary implication. Applying that principle, the Court found the amended Rule 17(1) did not authorise revision of a completed assessment because the assessment had attained finality before the amendment came into force. The Tribunal's view was upheld, and the assessee's challenge to the revised assessment failed.

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Issues: Whether the amendment to Rule 17(1) of the Madras General Sales Tax Rules, 1939, extending the period for revising escaped assessments from two years to three years, applied retrospectively to an assessment that had already become final.

Analysis: The governing principle is that a statute or amendment affecting vested rights is prima facie prospective unless the language expressly or by necessary implication makes it retrospective. Even where retrospectivity is intended, its operation is confined to the extent clearly warranted by the words used. The Court applied that principle to the amended rule and held that the assessment in question had already attained finality before the amendment came into force. As the amendment did not expressly or by necessary implication make the extended period applicable to completed assessments, it could not reopen a final assessment already made.

Conclusion: The amendment was not retrospective and did not authorise revision of the final assessment. The Tribunal's conclusion was upheld.

Final Conclusion: The revision was dismissed, and the assessee's challenge to the revised assessment failed.

Ratio Decidendi: An amendment enlarging the period for assessment or revision does not reopen assessments that had become final before the amendment unless retrospectivity is clearly expressed or necessarily implied.

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