Jurisdictional defect in notice service can be raised at any stage; invalid service rendered assessment proceedings void.

Valid service of notice under section 21 of the U.P. Sales Tax Act was a condition precedent to jurisdiction, so a defect going to the root of jurisdiction could be raised at any stage, including in remand, appeal or revision. Service by affixation was invalid because the prescribed alternative modes had not been exhausted. The notice was therefore not validly served, and the assessment proceedings were initiated without jurisdiction; the assessee could challenge the notice in remand proceedings.

---

---

Issues: Whether, in remand proceedings, an assessee could question the validity of notice under section 21 of the U.P. Sales Tax Act.

Analysis: Service of notice under section 21 was a condition precedent to the valid exercise of jurisdiction under that provision. A defect going to the root of jurisdiction could be raised at any stage, including in appeal or revision. On the facts, service by affixation was held invalid because the other prescribed modes had not been exhausted. As the notice was not validly served, the initiation of the assessment proceedings was without jurisdiction.

Conclusion: The assessee was entitled to question the validity of the notice in remand proceedings, and the answer to the referred question was in the affirmative, in favour of the assessee.

Ratio Decidendi: Where valid service of notice is a condition precedent to jurisdiction, a challenge to such service can be raised at any stage because an invalid notice renders the proceedings void ab initio.

---