These are four revisions filed by the Commissioner of Sales Tax, U. P. , under section 11 (1) of the U. P. Sales Tax Act (hereinafter REFERRED TO as the Act) challenging the judgment passed by the Sales Tax Tribunal, Muzaffarnagar Bench, Muzaffarnagar, dated 28th May, 1983, allowing the appeals of the respondent-assessee for the assessment years 1975-76, 1976-77 and 1977-78 arising out of proceedings under section 21 of the Act and for the assessment year 1978-79 arising out of original assessment proceedings under rule 41 (7) of the U. P. Sales Tax Rules (hereinafter REFERRED TO as the Rules ).

The respondent-assessee deals in manufacture and sale of mill board. In the assessment year 1978-79 mill board sold by the respondent-assessee has been treated as a kind of paper and covered under Notification No. ST-II-332/x-1012-1971 dated 15th November, 1971 and reassessment proceedings for the assessment years 1975-76, 1976-77 and 1977-78 started under section 21 of the Act have been held to be without jurisdiction by the Tribunal. The Revenue has come to this Court for quashing the aforesaid order passed by the Tribunal and raised the following two questions of law :

" (i) whether on the facts and under the circumstances of the case perusing the original assessment order the case was not of non-application of mind rather than change of opinion ? Is the assessing authority not competent to exercise his jurisdiction to reopen it under section 21 of the Act ?

(ii) Whether on the facts and in the circumstances of the case the Member, Sales Tax Tribunal, was justified in taxing the mill board as paper under Notification No. 332 dated 15th November, 1971, and not as an unclassified item ?"

As regards the first question the learned standing counsel appearing for the Revenue has urged that the Sales Tax Officer did not apply his mind to the question whether the mill board was covered by the term "paper" at the time of original assessment for the years 1975-76, 1976-77 and 1977-78 and in fact it was a case of non-application of mind by him at the time of original assessment and not a case of change of opinion by the Sales Tax Officer and he was fully justified in invoking the provisions of section 21 of the Act for reassessment and the Tribunal committed an error in holding otherwise. The learned counsel appearing for the respondent-assessee has, on the other hand, contended that the facts of the cases clearly establish that it was not a case of non-application of mind but the initiation of reassessment proceedings were based on mere change of opinion by the taxing authority at a subsequent stage. There is consensus of opinion that reassessment proceedings cannot be initiated on a mere change of opinion. The said proposition has also not been refuted by the learned standing counsel. It is not necessary to refer to the various decisions on that point. However, a reference may be made to the decision in the case of Commissioner of Sales Tax v. Jagdish Prasad Satish Prasad [1979] 43 STC 415 (All.); 1979 UPTC 820 wherein the principle laid down is as follows :

" In view of the pronouncement of the Supreme Court in the case of Commissioner of Sales Tax, U. P. v. Bhagwan Industries (P.) Ltd. [1973] 31 STC 293 at 300, it is, however, not necessary to do so, for, it has been held that the import of the words reason to believe as used in section 21 of the U. P. Sales Tax Act, 1948, is the same as in section 34 of the Income-tax Act, and the decisions given under section 34 of the Income-tax Act are appropriate for cases arising under section 21. This being so, the words reason to believe used in section 21 of the Act cannot be interpreted to encompass within its fold a mere change of opinion. It may be added that the phrase reason to believe means a reasonable belief on the part of the Sales Tax Officer that the turnover has escaped assessment. A belief cannot be reasonable in case it is purely subjective formed without ref