Unjust enrichment does not bar refund of excess interest on duty where the burden was not passed on; later amendment is prospective.

Refund of excess interest paid on delayed duty payment was held not to be barred by unjust enrichment because the invoices did not show recovery from customers and no debit notes were issued, so the burden was not passed on. The relevant period was 2005-2006, and the amendment extending unjust enrichment to refunds of interest was held prospective from 10-5-2008. The Revenue's objection therefore failed and the refund remained admissible.

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Issues: Whether refund of excess interest paid on delayed payment of duty was barred by unjust enrichment under section 11B, and whether the amendment introducing unjust enrichment for refund of interest applied to the relevant period.

Analysis: The refund related to excess interest paid on delayed duty payment. The invoices did not show recovery of such interest from customers, no debit notes were issued, and the burden of the excess interest could not be said to have been passed on. The relevant period was 2005-2006, when section 11B governed unjust enrichment for refund of duty and did not extend to refund of interest. The later amendment, effective from 10-5-2008, introducing unjust enrichment for interest refund, was held to be prospective.

Conclusion: The refund was not hit by unjust enrichment and the Revenue's objection failed.

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