Prospective tax-law amendment can end an exemption going forward; no vested right protects future benefit after legislative change.

A prospective amendment to the West Bengal Sales Tax Act's definition of "manufacture" could validly end the assessee's exemption for the unexpired period of its eligibility certificate from the date the amendment took effect. The earlier benefit was not withdrawn retrospectively; only future entitlement was affected. Exemption under a fiscal statute is a concession, not an irrevocable right, and promissory estoppel does not ordinarily prevent legislative alteration of a tax scheme. As the statutory scheme contained no express protection preserving the exemption after amendment, the assessee had no vested or accrued right to continue it.

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Issues: Whether the prospective amendment to the definition of "manufacture" under the West Bengal Sales Tax Act, 1994 could curtail the assessee's exemption for the unexpired period of the eligibility certificate and whether the assessee had acquired a vested or accrued right immune from such legislative change.

Analysis: The exemption had been granted under the statutory scheme on the basis of the then existing definition of "manufacture". The subsequent amendment omitting blending of tea was prospective and operated from the date it came into force. The benefit already enjoyed was not withdrawn retrospectively; only the continuing benefit for the future stood affected from the date of amendment. Exemption under a fiscal statute is a concession and not an irrevocable right, and the doctrine of promissory estoppel does not ordinarily operate against a statute or against legislative alteration of the tax regime. The statutory provisions relied upon by the assessee did not contain any express protection preserving the exemption despite the amendment.

Conclusion: The assessee had no vested right to continue the exemption after the prospective amendment, and the challenge to the withdrawal of the benefit failed.

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