Provisional assessment refunds cannot be reopened later, and unjust enrichment cannot be applied retrospectively to concluded claims.

Refund arising from finalisation of provisional assessment could not be reopened through a later show cause notice, because recoveries or refunds flowing from provisional assessment are governed by the adjustment mechanism of that scheme and not by the Section 11A/11B machinery once the assessment and refund sanction were concluded without challenge. The proceedings were therefore without jurisdiction and void. The doctrine of unjust enrichment introduced into the provisional assessment framework with effect from 25 June 1999 could not be applied retrospectively to a refund claim relating to 1 April 1997 to 30 September 1997, so the claim remained outside that later amendment.

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Issues: (i) Whether the show cause notice and the consequent proceedings could reopen and unsettle the refund arising from finalisation of provisional assessment; (ii) Whether the doctrine of unjust enrichment, introduced in the provisional assessment scheme from 25 June 1999, applied retrospectively to the refund claim.

Issue (i): Whether the show cause notice and the consequent proceedings could reopen and unsettle the refund arising from finalisation of provisional assessment.

Analysis: The refund arose directly from finalisation of provisional assessment. On the legal position recognised by the Supreme Court, recoveries or refunds arising upon adjustment of duty under provisional assessment are not governed by the recovery and refund machinery under Section 11A and Section 11B, as the case may be. The record also showed that the assessment finalisation and the refund sanction had already been completed, and no appeal had been filed by the Revenue against either order. In that situation, the subsequent notice attempting to reopen the concluded position lacked authority.

Conclusion: The show cause notice and the impugned proceedings were without jurisdiction and void ab initio.

Issue (ii): Whether the doctrine of unjust enrichment, introduced in the provisional assessment scheme from 25 June 1999, applied retrospectively to the refund claim.

Analysis: The refund related to the period 1 April 1997 to 30 September 1997, whereas the reliance on unjust enrichment was founded on an amendment introduced in the provisional assessment framework with effect from 25 June 1999. The legal effect of that introduction was prospective, and it could not be applied to claims that had arisen from an earlier period and had already been finalised under provisional assessment.

Conclusion: The doctrine of unjust enrichment did not apply retrospectively to the refund claim.

Final Conclusion: The refund sanctioned on finalisation of provisional assessment was held to be valid, and the subsequent attempt to recover it was set aside, leaving the assessee entitled to the consequential monetary reliefs recognized by law.

Ratio Decidendi: Refunds or recoveries flowing from finalisation of provisional assessment are governed by the adjustment mechanism of provisional assessment itself, and a later amendment introducing unjust enrichment cannot be applied retrospectively to such concluded claims.

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