Summarize the following court judgment. Civil Appeal Nos. 145 146/ 1972. (Appeals by Special Leave from the Judgment and Order dated 9 12 1970 of the Mysore High Court in Writ Petitions Nos. 2042 and 2065/70). Narayan Nettar	 for the appellant. R.M. Mehta	 for the respondent. The Judgment of the Court was delivered by KHANNA	 J. These two appeals by special leave are against the common judgment of the Mysore High Court whereby the High Court in two petitions under article 226 of the Constitution of India quashed two orders made by the Deputy Commissioner of Commercial Taxes appellant under section 21 of the Mysore Sales Tax Act	 1957 (hereinafter referred to as the Act). The respondent is an excise contractor. He was as sessed under the Act for the assessment years 1959 60 and 1960 61 as per orders dated March 21	 1963 made by the Commercial Tax Officer Raichur. Under those orders the taxable turnover of the respondent for the two years in question was determined after deducting the shop rent and the tree tax. For the assessment year 1959 60	 a sum of Rs. 2	10	542 was deducted and the net taxable turnover was determined to be Rs. 25	989. For the year 1960 61 a sum of Rs. 3	98	350 was deducted and the net taxable turnover was determined to be Rs. 26	657. The Commercial Tax Officer initiated proceedings under section 12A of the Act in respect of the aforesaid years because he was of the view that some items of turnover had escaped assessment. As per orders dated June 8	 1966 he made assessment by including in the turnover of the respond ent certain amounts which had escaped assessment under the original assessment orders dated March 21	 1963. The deduc tion in respect of shop rent and tree tax was	 however	 allowed to the respondent in orders dated June 8	 1966 as it had been allowed in initial orders dated March 21	 1963. On June 28	 1967 the appellant	 i.e.	 the Deputy Commis sioner of Commercial Taxes	 made two orders revising the orders dated June 8	 1966. In the said orders the appel lant disallowed the deduction which had been allowed to the respondent in respect of the shop rent. The appellant in those orders referred to the decision of this Court in Shinde Brother etc. vs Deputy Commissioner Raichur(1) and held that the amount of shop rent being not excise duty should not be deducted in computing the turnover of the respondent for the two years in question. The taxable turn over of the respondent for the two years in question was accordingly enhanced. (1) 595 The respondent made two applications for rectification of the orders of the appellant dated June 28	 1967. It was urged on behalf of the respondent that the revision of assessments was barred by limitation under section 21(3) of the Act and as such there was a mistake apparent on the record. The appellant rejected those applications. The respondent then preferred two appeals to the Sales Tax Appellate Tribunal. The Tribunal too rejected those ap peals on the ground that they were not maintainable. The respondent thereafter filed two petitions in the High Court under article 226 for the issuance of writs in the nature of certiorari for quashing the orders dated June 28	 1967. The High Court	 as already mentioned	 allowed both the peti tions and quashed orders dated June 28	 1967. In the opinion of the High Court	 orders dated June 28	 1967 made by the appellant were without jurisdiction since they had been made beyond the period of four years from the date of the assessment orders dated March 21	 1963. Mr. Narayan Nettar	 learned counsel for the appellant has contended in appeal before us that the period of four years mentioned in section 21 (3) of the Act should be computed from the orders dated June 8	 1966 made under section 12A of the Act and not from the initial orders of assessment dated March 21	 1963. The above stand has been controverted by Mr. Mehta	 who argued the case amicus curiae as no one appeared on behalf of the respondent. After giving the matter our consideration	 we are of the view that the contention advanced on behalf of the appel lant is well founded. Before	 however	 dealing with the matter	 we consider it appropriate to reproduce the relevant provisions of the Act. Section 12A of the Act relates to assessement of escaped turnover. Sub section (1) of that section at the relevant time read as under: "(1) Where for any reason the whole or any part of the turnover of a dealer has escaped assessment to tax or licence fee or has been assessed at a lower rate than the rate at which it is assessable	 the assessing authority may	 subject to the provisions of sub section (2)	 at any time within a period of five years from the expiry of the year to which the tax or licence fee relates	 assess to the best of its judgment	 the tax or li cence fee payable on the turnover referred to after issuing a notice to the dealer and after making such enquiry as it considers necessary. " Section 21 of the Act deals	 inter alia	 with revisional powers of the Deputy Commis sioner. Sub section (2) and (3) of that section read as under: "(2) The Deputy Commissioner may of his own motion call for and examine the record of any order passed or proceeding recorded under the provisions of this Act by a Commercial Tax Officer subordinate to him and against which no appeal has been preferred to him under section 20	 for the purpose of satisfying himself as to the legality or propriety of such order or as to the regularity of such proceeding and pass such order with respect thereto as he thinks fit. 4 112SCI/76 596 (3) In relation to an order of assessment passed under this Act	 the power under sub sections (1) and (2) shall be exercisable only within a period of four years from the date on which the order was passed. " The short question which arises for determination in these appeals is that in the event of an order having been made under section 12A of the Act	 what is the starting point for computing the period of four years	 mentioned in section 21 (3)	 for the exercise of the powers under section 21(2). Is it the initial assessment order or is it the order made under section 12A ? In the context of the present case	 the question to be answered is as to whether the period of four years is to be calculated from March 21	 1963 when the initial assessment orders were made	 or from June 8	 1966 when the orders under section 12A of the Act were made. So far as this question is concerned	 we are of the opinion that the period of four years should be calcu lated from June 8	 1966	 i.e.	 the date on which orders under section 12A of the Act were made. The reason for that is that once an assessment is reopened	 the initial order for assessment ceases to be operative. The effect of reopening the assessment is to vacate or set aside the initial order for assessment and to substitute in its place the order made on reassessment. The initial order for reassessment cannot be said to survive	 even partially	 although the justification for reassessment arises because of turnover escaping assessment in a limited field or only with respect to a part of the matter covered by the initial assessment order. The result of reopening the assessment is that a fresh order for reassessment would have to be made including for those matters in respect of which there is no allegation of the turnover escaping assessment. As it is we find that in the present case the assessment orders made under section 12A were comprehensive orders and were not confined merely to matters which had escaped assessment earlier. In the circumstances	 the only orders which could be the subject matter of revision by the appellant were the orders made under section 12A of the Act and not the initial assessment orders. In the case of V. Jagannathan Rao & ors. vs Commission er of Income tax and Exrcess Profits Tax	 Andhra Pradesh (1) this Court dealt with section 34 of the Indian Income tax Act	 1922 which relates to reassessment in the case of income escaping assessment. It was held by this Court that once assessment is reopened the previous under assessment is set aside and the whole proceedings star afresh. Ramaswami J. speaking for the Court observed: "Section 34 in terms states that once the Income tax Officer decides to reopen the assessment he could do so within the period prescribed by serving on the person liable to pay tax a notice containing all or any of the requirements which may be included in a notice under section 22(2) and may proceed to assess or reassess such income	 profits or gains. It is	 therefore	 manifest that once assess ment is (1) ITR 373. 597 reopened by issuing a notice under sub section (2) of section 22 the previous under assess ment is set aside and the whole assessment proceedings start afresh. When once valid proceedings are started under section 34(1)(b) the Incometax Officer had not only the juris diction but it was his duty to levy tax on the entire income that had escaped assessment during that year. " In the case of Commissioner of Sales Tax	 Madhya Pradesh vs H.M. Esufali H.M. Abdulali(1) this Court dealt with reassessment made under section 19 of the Madhya Pradesh General Sales Tax Act	 1958. It was held that when reas sessment is made	 the former assessment is completely reo pened and in its place fresh assessment is made. Hegde J. speaking for the Court observed: "What is true of the assessment must also be true of reassessment because reas sessment is nothing but a fresh assessment. When reassessment is made under section 19	 the former assessment is completely reopened and in its place fresh assessment is made. While reassessing a dealer	 the assessing authority does not merely assess him on the escaped turnover but it assesses him on his total estimated turnover. While making assessment under section 119	 if the assessing authority has no power to make best judgment assessment	 all that the assessee need do to escape reassessment is to refuse to file a return or refuse to produce his account books. If contention taken on behalf of the assessee is correct	 the assessee can escape his li ability to be reassessed by adopting an obstructive attitude. It is difficult to conceive that such could be the position in law." In International Cotton Corpn. (P) Ltd. vs Commercial Tax Officer	 HubIi & Ors. (2) this Court held that once can assessment order had been rectified and it was sought to make a further rectification of that order	 the period of limitation for making such further rectification would commence not from the date of the original assessment order but from the date of the earlier rectification order. Alagi riswami J. speaking for the Court in this context observed: "The other attack that the rectification order is beyond the point of time provided in Rule 38 of the Mysore Sales Tax Rules is also without substance. What was sought to be rectified was the assessment order rectified as a consequence of this Court 's decision in Yaddalam 's case. After such rectification the original assessment order was no longer in force and that was not the order sought to be rectified. It is admitted that all the rectification orders would be within time calculated from the original rectification order. Rule 38 itself speaks of 'any order ' and there is no doubt that the rectified order is also 'any order ' which can be rectified under Rule 38." ; I.T.R. 271. (2) [1975] 2 S.C.R. 345. 598 Although the above case related to an order which had been subsequently rectified	 the principle laid down therein would	 in our opinion	 be also applicable in cases where reassessment is made on the ground that certain amounts of turnover had escaped assessment. Before we conclude	 we may observe that according to section 33B of the Indian Income tax Act	 1922 the Commis sioner cannot revise an order of reassessment made under the provisions of section 34 of the Act. Likewise	 sub section (2) of section 263 of the Incometax Act	 1961 expressly prohibits the revision by the Commissioner of Income tax of an order of reassessment made under section 147 of Act. No such prohibition in the provisions of the Act with that Act. Nosuch prohibition brought to our notice. which we are concerned has	 however	 been brought to our notice. We would	 therefore	 accept the appeals	 set aside the judgment of the High Court and dismiss the petitions under article 226 filed by the respondent. Looking to all the facts	 we leave the parties to bear their own costs in this Court as well as in the High Court.

In respect of the assessment years 1959 60 and 1960 61	 fresh assessments were made under section 12A of the Mysore General Sales Tax Act 1957 by the 	 Commercial Tax Offi cer. By his order dated June 8	 1966	 certain amounts which had escaped assessment under the original assessment orders dated March 21	 1963 were included in the turnover of the respondent	 but the deductions in respect of shop rent and tree tax were	 however	 allowed as in the initial orders. The appellant	 in exercise of the powers under section 21(2) of the Act	 by his orders dated June 28	 1967 revised the orders dated June 8	 1966 disallowing the deductions in respect of the shop rent	 following the decision of this Court in Shinde Brother etc. vs Deputy Commissioner Raichur Two rectification applications and the two appeals therefrom on the ground that the revisions of assessment were barred by limitation under section 21(3) of the Act and	 as such	 there was a mistake apparent on the record were rejected as not maintainable. However	 the writ petitions filed were allowed by the High Court holding that the orders dated June 28	 1967 were without jurisdic tion since they had been made beyond the period of four years from the date of the initial assessment orders dated March 21	 1963. On appeals by special leave to this Court	 HELD: The contention advanced on behalf of the appel lants that the period of four years mentioned in section 21(3) of the Act should be computed from the orders dated June 8	 1966 made under S 12A of the Act and not from the ini tial orders of assessment dated March 21	 1963 is well founded. [595 C D] Once an assessment is reopened the initial order for as sessment ceases to be operative. The effect of reopening the assessment is to vacate or set aside the initial order for assessment and to substitute in its place the order made on reassessment. The initial order for reassessment cannot be said to survive even partially although the justification for dessessment arises because of turnover escaping assess ment in a limited field or only with respect to a part of the matter covered by the initial assessment order. The result of reopening the assessment is that a fresh order for reassessment would have to be made including for those matters in respect of which there is no allegation of the turnover escaping assessment. [596 D E] In the present case the assessment orders made under section 12A were comprehensive orders and were not confined merely to matters which had escaped assessment earlier and the only orders which could be the subject matter of revision by the appellant were the orders made under section 12A of the Act and not the initial assessment orders. [596 E F] J. Jaganmohan Rao & Ors. vs Commissioner of Income tax and Excess Profits Tax	 Andhra Pradesh [1970] 1 S.C.R. 726=75 ITR 373; Commissioner of Sales Tax	 Madhya Pradesh vs H.M. Esufali H.M. Abdulali ITR 271	 followed. International Cotton Corporation (P) Ltd. vs Commercial Tax Officer	 HubIi & Ors. [1975] 2 S.C.R. 345	 applied.