Promissory estoppel cannot defeat statutory tax powers where the promised exemption is unauthorised or contrary to law.

An assessee claiming sales tax exemption under an industrial incentive scheme and eligibility certificates could not show a legally enforceable entitlement overriding the taxing statute. The Court reiterated that promissory estoppel is an equitable doctrine, but it cannot restrain the State from performing statutory duties, exercising lawful powers, or changing policy in public interest. It also cannot be used to compel an assurance that is unauthorised, ultra vires, or contrary to law. On the facts, the assessment and revisional orders disclosed no infirmity, so the exemption claim and the plea of promissory estoppel failed and the tax orders were sustained.

---

---

Issues: Whether the assessee was entitled to sales tax exemption on the basis of the industrial incentive scheme and eligibility certificates, and whether the doctrine of promissory estoppel could be invoked to invalidate the assessment and revision orders.

Analysis: The claim for exemption rested on the 1986 industrial policy and the eligibility certificates issued by the implementing agency, but the writ petition contained no material particulars showing a legally enforceable entitlement overriding the taxing statute. The Court held that promissory estoppel is an equitable doctrine reflected in Section 115 of the Indian Evidence Act, 1872, but it cannot prevent the State from performing statutory duties, exercising lawful powers, or altering policy in public interest. A public authority cannot be estopped from acting within its statutory framework, and the doctrine cannot be used to compel an assurance that is unauthorised, ultra vires, or contrary to law. On the facts, the assessment order and the revisional order disclosed no infirmity warranting interference.

Conclusion: The exemption claim failed, the plea of promissory estoppel was rejected, and the assessment and revisional orders were upheld.

Final Conclusion: The writ petition was dismissed and the tax authorities' orders were sustained.

Ratio Decidendi: Promissory estoppel cannot be invoked against the State to defeat statutory powers or obligations, or to compel a benefit that is unauthorised or contrary to law, especially where public interest is involved.

---