Sections 16 and Section 32 of the TNGST Act, the Hon'ble Division Bench pointed out that, according to Section 16(1)(a), where, for any reason, the whole or any part of the turnover of business of a dealer has escaped assessment to tax, the assessing authority may, subject to the provisions of the sub-section (2) at any time, within a period of 5 years from the expiry of the year to which the tax relates, determine to the best of its judgment, the turnover, which has escaped the assessment, and assess the tax payable on such turnover after making such enquiry, as it may consider necessary and after giving the dealer a reasonable opportunity to show cause against such assessment. Therefore, even if a direction was given by the Deputy Commissioner to reopen the assessment, the Assessing Officer can reopen the assessment only if there is a period of five years for reopening as contemplated under Section 16(1)(a) of the Act. 18. In the case of P.Narayanasamy (supra), the question was whether, while exercising jurisdiction under Section 34 of the TNGST Act, 1959, the Joint Commissioner can revise the order passed by the authorities below only on the basis of the materials available on record. The Hon'ble Division Bench held that the Joint Commissioner cannot rely upon the extraneous materials, which were not on record before the order was passed by the lower authorities. 19. In the instant case, the material sought to be relied upon was available with the Assessing Officer for the relevant assessment year. As noticed, the Assessing Officer himself, in the subsequent assessment orders has referred to the very same materials, which are contained in the earlier notice, and hence, the impugned notices are unsustainable. One more important factor to be noted is that the petitioners' sellers, viz., i) M/s. Aashana Enterprises, ii) M/s.Kamelesh Enterprises, and iii) M/s. Shreyanash Ispat Chennai, Pvt. Ltd. have been assessed to tax for the assessment year, viz., 1998-99 vide the assessment orders, dated 16.02.2000, 14.02.2000 and 27.01.2000, and those assessment orders are intact, and this one more reason to hold that the impugned