Valid service of reassessment notice is a jurisdictional ; participation cannot cure defective service or create estoppel.

Service of notice under section 21 of the U.P. Sales Tax Act is a jurisdictional condition precedent to reassessment, so notice must be validly issued and served on the dealer; service on a stranger does not confer power to reopen assessment. The assessee's appearance and participation do not cure the defect, because consent, acquiescence, waiver, or estoppel cannot create jurisdiction where the statutory precondition has not been met. The reopening was therefore invalid for want of proper service, and the defect could not be neutralised by participation in the proceedings.

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Issues: (i) whether service of notice under section 21 of the U.P. Sales Tax Act on a stranger was a valid service on the assessee and conferred jurisdiction to reopen assessment; (ii) whether the assessee's appearance and participation in the proceedings cured the defect in service or created an estoppel against challenging jurisdiction.

Issue (i): whether service of notice under section 21 of the U.P. Sales Tax Act on a stranger was a valid service on the assessee and conferred jurisdiction to reopen assessment.

Analysis: Notice under section 21 is a jurisdictional requirement and a condition precedent to the exercise of power to assess or reassess escaped turnover. The statutory words require notice to the dealer, and the authority acquires no jurisdiction unless the notice is validly issued and served on the person liable. Service on a stranger does not satisfy the statutory mandate.

Conclusion: The notice was not validly served on the assessee and the reassessment proceedings were without jurisdiction.

Issue (ii): whether the assessee's appearance and participation in the proceedings cured the defect in service or created an estoppel against challenging jurisdiction.

Analysis: Where jurisdiction is absent because the statutory condition precedent has not been fulfilled, consent, acquiescence, participation, waiver, or estoppel cannot create jurisdiction. The bar on challenge to territorial or pecuniary jurisdiction does not apply to a defect going to the very existence of jurisdiction under section 21, and equitable considerations cannot validate a proceeding forbidden by statute.

Conclusion: Participation did not cure the invalid service and no estoppel arose against the assessee.

Final Conclusion: The reopening was invalid for want of proper service of notice, and the defect could not be neutralised by the assessee's participation in the proceedings.

Ratio Decidendi: When a statute makes service of notice a condition precedent to reassessment, valid service is indispensable to jurisdiction and cannot be replaced or cured by consent, acquiescence, waiver, or estoppel.

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