Summarize the following court judgment. il Appeal No. 1101 of 1967	. Appeal by certificate from the judgment and order dated September 28	 1966 of the Calcutta High Court in Appeal No. 7 of 1965. G. L. Sanghi	 B. D. Sharma and section P. Nayar	 for ;the appellant. A. K. Sen	 B. P. Maheshwari and Shambhu Nath Chunder	 for the respondent. The Judgment of the Court was delivered by Beg	 J. The National Tobacco Co. of India Limited (herein after referred to as "the Company")	 the Respondent in the appeal before us	 manufactures Cigarettes	 at its Factory in Agrapara	 upon which Excise duty is vied by the appellant	 the Assistant Collector of Central Excise	 Calcutta Division (hereinafter referred to as "the Collector"). The rates at which the Excise duty was imposed upon the cigarettes of the Company under the provisions of the Central Excise and Salt Act of 1944 (hereinafter referred to as "the Act") were varied	 from time to time	 by the provisions of Finance Acts of 1951 and 1956 and the Additional Duties of Excise (Goods of Special Importance) Act of 1957. The Collector maintained an office at the factory itself for the levy and collection of tax. The Company was required to furnish quarterly consolidated price lists which used to be accepted for purposes of enabling the Company to clear its goods	 but	 according to the Collector	 these used to be verified afterwards by obtaining evidence of actual sales in the market before issuing final certificates that the duty had been fully paid up. The particulars of the cigarettes to be cleared were furnished by the Company on forms known as A.R.1 forms required by Rule 9 of the Central ' Excise Rules. For facilitating collection of duty	 the Company	 maintained a large sum of money in a current account with the 825 Central Excise authorities who used to debit in this account the duty leviable on each stock of cigarettes allowed to be removed. This current account	 known as "personal ledger account"	 was maintained under the third proviso to Rule 9 which lays down: 9(1) " * * * * * * Provided also that the Collector may	 if he thinks fit	 instead of requiring payment of duty in respect of each separate consignment of goods removed from the place or premises specified in this behalf	 or from a store room or warehouse duly approved	 appointed or licensed by him keep with any person dealing in such goods an account current of the duties payable thereon and such account shall be settled at intervals not exceeding one month and the account holder shall periodically make deposit therein sufficient in the opinion of the Collector to cover the duty due on the goods intended to be removed from the place of production	 curing	 manufacture or storage". It appears that the company used to furnish its quarterly price lists to the Collector on forms containing nine columns including one to show the "distributors ' selling price". Until July 1957	 so long as this form was used by the Company	 no difficulty seems to have been experienced in checking the prices. But	 after this column was dropped from the new form of six columns	 the excise authorities seem to have encountered some difficulty in valuing the cigarettes for vying excise duty. They. ' therefore	 changed the basis of assessment itself from "the Distributors" Selling Price" to "the wholesale cash selling price at which stockists or agents are selling the same to an independent buyer in the open market". They held the view that such a charge could be made having regard to the provisions of Section 4 of the Act. The Deputy Superintendent of Central Excise informed the Company	; of this change of basis on 5 11 1958 by a letter which also asked the Company to furnish its price lists immediately "for determining the correct assessable value" of its cigarettes. On 7th November		 1958	 the Deputy Superintendent served a notice upon the Company demanding	 payment of a sum of Rs. 1.67	072	40 as basic Central Excise duty and Rs. 74	574	85 as additional Central Excise duty on account of short levy for a certain brand of cigarettes cleared from the Company 's factory from 10th August	 1958 to 5th November	 1958. On 12 11 1958	 the Deputy Superintendent sent another notice demanding payment of a sum of Rs. 6	16	467	49 as basic Central Excise duty and Rs. 2	10	492	15 as additional central excise duty for short levy in respect of some brands of cigarettes cleared from the factory between 1 11 1957 to 9 8 1958. On 13 11 1959. (the Deputy Superintendent sent a 826 third notice to the Company under Rule 10 A of the Central Excise Rules 1944	 demanding payment of Rs. 40	726	48 as basic Central Excise duty and Rs. 16	958.50 as additional duty for short levy in respect of various brands. The Company applied to the Calcutta High Court under Article 226 of the Constitution against the three notices mentioned above	 one of which specifically under Rule 10 A and the other two under Rule 10 of the Central Excise Rules. A learned single Judge of that Court quashed the notices by his order of 15 2 1960 on the ground that the Company had not been given any opportunity of being heard so as to be able to meet the material collected behind its back which formed the basis of the demands under the aforesaid three notices. On a joint request of both ides. the High Court did not decide the question whether notices of demand 	were time barred. But	 the learned Judge said : "Nothing in this order will prevent the respondent from proceeding to take any step that may be necessary for such assessment or for the realisation of the revenue in accordance with the law". The learned Judge had also held that neither the basis adopted by the company nor that put forward by the Collector was correct. The learned Judge pointed out the correct basis which was considered by him to be in consonance with the provisions of Section 4	 sub.s(a) of the Act. He indicated the various factors required by Section 4 of the Act which had to be taken into account and held: "The determination as to whether a wholesale market exists at the site of the factory or the premises of manufacture or production etc. or which is the nearest wholesale market	 or the price at which the goods or goods of like kind and quality are capable of being sold must necessarily be a complicated question and must be determined carefully upon evidence and not arbitrarily. Such determination cannot wholly be made ex parte	 that is to say	 behind the back of the assessee. A satisfactory determination can only be made by giving all information to the assessee and after giving the assessee an opportunity of establishing his own point of view	 or checking and/or challenging any material or evidence upon which the Excise Authorities wish to depend. " As no appeal was filed by either side against this decision	 it became final and binding between parties before us so that the question whether the High Court has correctly interpreted Section 4 of the Act in determining the basis on which the excise duty leviable could be assessed is not under consideration here. 827 When the case went back to the Collector	 he issued a fresh notice on 24 4 1960. As the validity of this notice is the real question now in issue in the appeal before us	 it may be reproduced in toto here. It turns as follows: Registered A/D GOVERNMENT ' OF INDIA Collectorate of Central Excise Office of the Assistant Collector of Central Excise	 Calcutta I Division (5	 Clive Row)	 Calcutta NOTICE C. No. VI(b)14/3/58/3886 Dated 21st April. 	 1960 TO M/s. National Tobacco Co. (India) Ltd.	 Agarpara	 24 Parganas. In connection with the assessment of Central Excise duties for the periods : 1. from 1st October	 1957 to 5th November	 1958 in respect of 316	885	000 of "No. Ten" brand Cigarettes. from 1st January	 1958 to 28th January 	 1958 in respect of 6	600	000 of "D.L.T. Mag" Cigarettes. from 1st January	 1958 to 5th February	 1958 in respect of 9594	000 of "May Pole" Cigarettes '. from 1st January	 1958 to 7th February	 1958 in respect of 3143	500 "Carltons Gold Seal" Cigarettes. V. from 1st January 1958 to 31st January	 1958 in respect of 1471	250 of "John Peel" Cigarettes. from 1st January	 1958 to 16th January	 1958 in respect of 8200	000 of "Light House" Cigarettes. from 1st January	 1958 to 16th January	 1958 in respect of 9070	000 of "Gold Link" Cigarettes. Please note that a sum of Rs. 10	05	133.25 np. (Rupees 10 lads five thousand one hundred thirty three and twenty five naya paise only) as basic Central Excise duty and a total sum of Rs. 3	43	208.25 np. (Rupees three lacs forty three thousand two hundred eight and twenty five naya paise only) as additional duty had been provisionally debited in your account on the basis of the price list supplied to us by you for the quarters 828 (i) beginning October	 1957 dated 17th October	 1957. (ii) beginning January	 1958 dated nil. (iii) beginning April	 1958 dated 14th April	 1958	 and (iv) beginning July	 1958 dated 14 7 58	 and (v) beginning October	 1958	 dated nil. We now propose to complete the assessments for the said periods from the evidence in our possession from which it appears : (i)that there is no wholesale market for the goods covered by your price lists in or near the factory or the 'Place of manufacture and that the nearest wholesale market for the sale is the Calcutta market. (ii) the wholesale cash price of the articles in question at the time of sale and/or removal of the 		goods at the Calcutta market at which goods of like kind or quality are sold or are capable of being sold have been ascertained by us and the evidence at our disposal reveals that the prices quoted by you in your price list are not correct. The prices at	 as per chart annexed hereto which has been prepared on the basis of available evidence in terms of section 4 (a) 	 of the Central Excise and Sale Act	 1955. The vouchers mentioned in the chart are available for your inspection at any time next week during office hours. After obtaining inspection of the vouchers please attend at our office at 5 Clive Row	 Calcutta on 2nd May 1960 at 10.30 a. 'M. for the purpose of discussing the points mentioned above 4. We are prepared to give you a personal hearing with regard to all the points indicated above. If you have any evidence in support of your contention you are at liberty to produce the same at the time of bearing. Thereafter please note that we propose to make the final assessment in accordance with law. Sd./ (N. D. MUKhERJEE) Assistant Collector of Central Excise	 Calcutta I Division	 Calcutta" The Company challenged the validity of this notice by means of a second petition for Writs of Prohibition and Mandamus against the Collector on the ground that the notice was barred by time 829 and was issued without jurisdiction so that no proceedings founded on it could be taken. It was prayed that the Collector may be ordered to cancel the notice. The petition was allowed by a learned Single Judge of the Calcutta High Court on 3 1 1964 on the ground that such a notice was barred by the provisions of Rule 10 of the Central Excise Rules 'because the notice was held to be fully covered by Rule 10 and by no other rule. A Division Bench of the High Court confirmed this view on 8 9 1966 and dismissed the Collector 's appeal. The case having been certified	 under Article 133(a)	 (b) and (c) for an appeal to this Court	 this question is before us now. The learned Single Judge as well as the Division Bench of the Calcutta High Court said that there was not enough material on record to conclude that there was any "provisional assessment" under Rule 10 B (deleted on 1 8 1959 and substituted by Rule 9 B) which laid down: "10B. PROVISIONAL ASSESSMENT OF DUTY (1) Notwithstanding anything contained in these rules (a) There the owner of any excisable goods makes and subscribed a declaration before the proper Officer to the effect that he is unable for want of full information to state precisely the real value or description of such goods in the proper Form : or (b) Where the owner of any goods has furnished full information in regard to the real value or description of the goods	 but the proper Officer requires further proof in respect thereof; or (c) Where the proper Officer deems it expedient to subject any excisable goods to any chemical or other test	 The proper Officer may direct that the duty leviable on such goods may	 pending the pro duction of such information or proof or pending the completion of any such test	 be assessed provisionally. (2) When the owner of any goods in respect of which the duty has been assessed provisionally under sub rule(1) has paid such duty	 the proper Officer may make an order allowing the goods to be cleared for home consumption or for exportation	 as case may be and such order shall be sufficient authority for the removal of the goods by the owner: Provided that before making any such order the proper officer shall require the owner to furnish a bond in the proper form binding the Owner to pay the differen 830 tial duty When the final assessment is made. (3) When the duty leviable on such goods is assessed finally in accordance with the provisions of these rules	 the duty provisionally assessed shall be adjusted against the duty finally assessed	 and if the duty provisionally assessed	 falls short of	 or is in excess of	 the duty finally assessed. the owner of the goods shall pay the deficiency or be entitled to a refund	 as the case may be." No order directing provisional assessment	 contemplated by Rule 10 B	 (applicable at the relevant time) has been placed before us. Nor was the Company asked by the Collector to furnish a bond to pay up the difference after making a final assessment as was required under Rule 10 B. It was	 however	 contended for the Collector that the execution of a bond	 for the satisfaction of the Collector	 could be dispensed with in a case where the Company kept a large sum of money in deposit in the "personal ledger account" to guarantee its ability to meet its liabilities. It was also pointed out that the learned Single Judge as well as the Division Bench had found that the practice of provisionally approving the price lists supplied by the Company	 pending acceptance of their correctness after due verification	 had been established as a mater of fact. It was submitted that this was substantially a "provisional assessment" covered by Rule 10 B	 although it may not conform to the technical procedural requirements of such an assessment. Even if the making of debit entries could	 on the facts of the case	 be held to be merely provisional think that what took place could not be held to be a "provisional assessment" within the provisions of Rule 10 B which contemplated the making of an order directing such an "assessment" after applying_ the mind to the need for it. Before proceeding further we will deal with the question whether the Division Bench correctly refused to permit an argument that the impugned notice of 24 4 1960 fell under Rule 10 A. The ground given for this refusal was that such a case was neither taken before 'the learned Single Judge nor could be found in the grounds of appeal despite the fact that the appellant had ample opportunity of amending its Memorandum of appeal. The appellant has	 however	 relied on a previous intimation given to the counsel for the respondent that such a contention would be advanced at the hearing of the appeal and also on an application dated 21 3 1966 praying for permission to add the alternative ground that the impugned notice fell under Rule 10 A. We think that this refusal was erroneous for several reasons. Firstly the Company having come to Court for a Writ of Pro hibition on the ground that the impugned notice was issued with 831 out jurisdiction had necessarily to establish the case which it sets	 up in paragraph 25 of its Writ Petition	 that the notice was not authorised by the rules including Rule 10 A. As the notice of 21 4 1960 was followed on 4 5 1960 by a correction by another notice of certain statements both the notices were assailed in paragraph 25 (ii) in the following words "The respondent has mala fide and without jurisdiction issued the said impugned notices pretending to falsely state that the aggregate sum therein mentioned has been provisionally debited in your petitioner 's account and pretending to intimate	 to your petitioner that the respondent proposed to complete the assessment	 And thereby	 he is seeking	 under the guise of completing an alleged assessment which had already been completed and duty in respect whereof had already been paid	 to do indirectly what he could not do directly inasmuch as Rule 10A of the said Rules has no application to the facts of the case and inasmuch as recovery of any duty which might have been short levied under Rule 10 of the Rules is barred by limitation". This assertion was met by a categorical denial by the Collector in paragraph 26(ii) of the Collector 's affidavit in reply where it was stated that it was denied "that Rule 10 A of the said Rules had no application to the facts of the case as alleged or that the recovery of any duty which had been short levied was barred by limitation under Rule 10 of the said Rules as alleged or at all". Thus	 the applicability of Rule 10 A was very much in issue. Secondly	 We find	 from the Judgment of the learned Single Judge that	 as the burden lay upon the petitioning Company to demonstrate	 for obtaining a Writ of Prohibition	 that the impugned notice was not authorised by any rule	 its counsel had contended '		 inter alia	 that the notice did not fall under Rule 10 A. The question was thus considered by the learned Single Judge. Thirdly	 the question whether the Collector did or did not have the power to issue the impugned notice under or with the aid of Rule 10 A was a question of law and of jurisdiction. going to the root of the case	 which could be decided without taking further evidence. Indeed	 as the burden was upon the petitioning Company to show that the impugned notice was issued without jurisdiction	 a finding that the notice did not fall even within Rule 10 A was necessary before a Writ of Prohibition could issue at all. We think that the Division Bench ought to have permitted the question to be argued	 subject to giving due opportunity to the petitioning Company to meet it on such	 832 terms as the Court thought fit	 even if the point was not taken in the grounds of appeal. Therefore	 we will consider this question also. Rule 10 of the Central Excise Rules	 ran as follows "10. Recovery of duties or charges short levied	 or erroneously refunded When duties or charges have been short levied	 through inadvertence	 error	 collusion or mis construction on the part of an officer	 or through misstatement as to the quantity	 description or value of such goods on the part of the owner	 or when any such duty or charge	 after having been levied	 has been owing to any such 'cause	 erroneously refunded	 the person chargeable with the duty or charge	 so short levied	 or to whom such refund has been erroneously made	 shall pay the deficiency or pay the amount paid to him in excess	 as the case may be	 on written demand by the proper officer being made within three months from the date on which the duty or charge was paid or adjusted in the owners account current	 if any	 or from the date of making the refund". Rule 10 A reads as follows: "10 A Residuary powers for recovery of sums due to Government. Where these Rules do not make any specific provision for the collection of any duty	 or of any deficiency in duty if the duty has for any reason been short levied	 or of any other sum of any kind payable to the Central Government under the Act or "these Rules	 such duty	 deficiency in duty or sum shall	 on a written demand made by the proper officer	 be paid to such person and at such time and place	 as the proper officer may specify. " The two rules set out above occur in Chapter III of the Central Excise Rules 1944 headed "Levy and Refund of	 and Exemption from Duty". Rule 7 merely provides that the duty leviable on the goods will be paid at such time and place and to such	 person as may be required by the rules. Rule 8 deals with power to authorise exemptions in special cases. Rule 9(1) provides for the time and manner of payment of duty. This rule indicates that ordinarily the duty leviable must be paid before excisable goods are removed from the place where they are manufactured or stocked	 and only after obtaining the permission of the officer concerned. The third proviso 833 to Rule 9 has already been set out above. Rule 9(2) provides for the recovery of duty and imposition of penalty in cases where Rule 9 sub. r (1) is violated. Rule 9A specifies the date with reference to which the duty payable is to be determined. We are 	not concerned here with Rules 11 to 14 dealing with refunds	 rebates	 exports under bonds and certain penalties for breaches of Rules. Rule 52 and 52 A	 found in Chapter V	 dealing with a number of matters relating to "Manufactured Goods"	 may also be cited here : "52. Clearance on payment of duty When the manufacturer desires to remove goods on payment of duty	 either from the place or a premise specified under rule 9 or from a store room or other place of storage approved by the Collector under rule 47	 he shall make application in triplicate (unless otherwise by rule or order required) to the proper officer in the proper Form and shall deliver it to the Officer at least twelve hours (or such other period as may be elsewhere prescribed or as the Collector may in any particular case require or allow) before it is intended to remove the goods. The officer	 shall	 thereupon	 assess the amount of duty due on the goods and on production of evidence that this sum has been paid into the Treasury or paid to the account of the Collector in the Reserve Bank of India or the State Bank of India	 or has been despatched to the Treasury by money order shall allow the goods to be cleared". "52A. Goods to be delivered on a Gate pass (1) No excisable goods shall be delivered in a factory except under a gatepass in the proper form or in such other form as the Collector may in any particular case or class of cases prescribe signed by the owner of the factory and countersigned by the proper officer. " It will be noticed that in Chapter III	 the term "assessment" was used only in the former rule 10 B	 corresponding to the present rule 9 B	 while dealing with provisional assessment of duty. But	 Rule 52 shows that an "assessment" is obligatory before every removal of manufactured goods. The rules however	 neither specify the kind of notice which should precede assessment nor lay down the need to pass an assessment order. All we can say in that rules of natural justice have to be observed for	 as was held by this Court in K. T. M. Nair vs State of Kerala(1)	 "the assessment of a tax on person or property is atleast of a quasi judicial character". (1) ; @ 94. L Sup. CI/73 834 Section 4 of the Act lays down what would determine the value of excisable goods. But	 the Act itself does not specify a procedure for assessment presumably because this was meant to be provided for by the rules. Section 37(1) of the Act lays down that "the Central Government may make rules to carry into effect the purposes of this Act". Section 37	 sub. s (2)	 particularises without prejudice to the generality of the foregoing power" that "such rules may provide for the assessment and collection of duties of excise	 the authorities by whom functions under this Act are to be discharged 	 the issue of notice requiring payment	 the manner in which the duty shall be payable	 and the recovery of duty not paid". It is clear from Section 37 that " assessment and collection of duties of excise" is part of the purposes of the Act	 and Section 4	 dealing with the determination of value for the purposes of the duty	 also seems to us to imply the existence of a quasi judicial power to assess "he duty payable in cases of dispute. "Collection"	 seems to be a term used for a stage subsequent to "assessment". In a case where the basis of a proposed assessment is disputed or where contested questions of fact arise	 a quasi judicial procedure has to be adopted so as to correctly assess the tax payable. Rule 52 certainly makes an "assessment" obligatory before removal of goods unless the procedure for a "provisional assessment" under Rule 10 B (now rule 9 B) is adopted. But	 if no quasi judicial pro ceeding	 which could be described as an "assessment" either under Rule 52 or "Provisional assessment" under Rule 10 B (now Rule 9 B) takes place at the proper time and in accord ance with the rules	 is the Collector debarred completely afterwards from assessing or completing assessment of duty payable ? That seems to us to be the real question to be decided here. One of the arguments on behalf of the Collector was that no "assessment"	 for the purpose of determining the value of excisable goods	 having taken place in the case before us	 there could be no "levy" in the eye of law. It was urged that	 even if there was no "provisional assessment"	 as contemplated by Rule 10 B	 whatever took place could	 at the most	 be characterised as an "incomplete assessment"	 which the Collector could proceed to complete	 even after the removal of the goals. It was contended that such a case would be outside the purview of Rule 10 as it was not determined whether there actually was a short levy. Hence	 it was submitted there was no question of a proceeding barred by the limitation prescribed for making a The demand for a short levy in certain specified circumstances. Division Bench	 while repelling this contention	 held : "In the present case	 it appears that the procedure adopted was that the respondents issued a price list 835 quarterly. In that price list	 they gave their own estimate as to the value of the goods. For the time being the excise authorities accepted the value so given	 and gave a provisional certificate to that effect	 intending to check the market value and then finally determine the value later on. The procedure for issuing price list of approving the same provisionally and accepting payment therefore according to the estimate of the manufacturer	 is a procedure which is not to be found either in the Act or the Rules". It may be observed that this finding	 that the procedure of a provisional acceptance of the Company 's estimates was adopted	 seems inconsistent with another finding that what took place was a final adjustment of accounts within the purview of the 3rd proviso to Rule 9	 set out above	 constituting a "levy" accord to law. The Division Bench appears to have regarded this procedure of an almost mechanical levy as equivalent to a complete assessment followed by the payment of the tax which constituted a valid "levy". Hence	 it concluded that	 there being a legally recognised levy	 the only procedure open to the Collector for questioning its correctness was one contemplated by Rule 10 so that a demand for a short levy had to be made within 3 months of the final "settlement of accounts" as provided specifically by Rule 10. The Division Bench considered this procedure to be an alternative to an assessment under Rule 52 at the proper time and also :to a provisional assessment in accordance with the procedure laid down in Rule 10 B. But	 to regard the procedure under Rule 10 as an alternative to an assessment would be to overlook that it presupposes an assessment which could be reopened on specified grounds only within the period given there. The term "levy" appears to us to be wider in its import than the term "assessment". It may include both "imposition" of a tax as well as assessment. The term "imposition" is gene rally used for the	 levy of a tax or duty by legislative provision indicating the subject matter of the tax and the rates at which it has to be taxed. The term "assessment"	 on the other hand	 is generally used in this country for the actual procedure adopted in fixing the liability to pay a tax on account of particular goods or property or whatever may be the object of the tax in a particular case and determining its amount. The Division Bench appeared to equate "levy" with an "assessment" as well as with the collection of a tax when it. held that "when the payment of tax is enforced	 there is a levy". We think that	 although the connotation of the term "levy" seems wider than that of "assessment"	 which it includes	 yet	 it does not seem to 836 us to extend to "collection". Article 265 of the Constitution makes a distinction between "levy" and "collection". We also find that in N. B. Sanjana Assistant Collector of Central Excise	 Bombay & Ors. vs The Elphinstone Spinning & Weaving Mills Co. Ltd.	A(1)	 this Court made a distinction between "levy" and "collection" as used in the Act and the Rules before us. It said there with reference to Rule 1 0 : "We are not inclined to accept the contention of of Dr. Syed Mohammad that the expression 'levy ' in Rule 10 means actual collection of some amount. The charging provision Section 3(1) specifically says. 'There shall be levied and collected in such a manner as may be prescribed the duty of excise . ' It is to be noted that subsection (i) uses both the expressions "levied and collected" and that clearly shows that the expression 'levy ' has not been used in the Act or the Rules as meaning actual collection". We are	 therefore	 unable to accept the view that	 merely because the "account current"	 kept under the third proviso (erroneously mentioned as second proviso by the Division Bench) to Rule 9	 indicated that an accounting bad taken place	 there was necessarily a legally valid or complete levy. The making of debit entries was only a mode of collection of the tax. Even if payment or actual collection of tax could be spoken of as a de facto "levy" it was only provisional and not final. It could only be clothed or invested with validity after carrying out the obligation to make an assessment to justify it. Moreover	 it is the process of assessment that really determines whether the levy is short or complete. It is not a factual or presumed levy which could	 in a disputed case	 prove an "assessment". This has to be done by proof of the actual steps taken which constitute "assessment". Undoubtedly	 a mechanical adjustment and ostensible settle ment of accounts	 by making debit entries	 was gone through in the case before us. But	 we could not equate such an adjustment with an assessment	 a quasi judicial process which involves due application of mind to the facts as well as to the requirements of law	 unless we were bound by law to give an unusual interpretation to the term "assessment". Here	 we do not find any such definition of assessment or any compelling reason to bold that what could at most be a mechanical provisional collection	 which would become a "levy" in the eve of law only after an "assessment"	 was itself a levy or an assessment. Rules 10 and 10A	 placed side by side	 do raise difficulties of interpretation. Rule 10 seems to be so widely worded as to (1) ; 2045. 837 cover any "inadvertence	 error	 cullusion or misconstruction on the part of an officer"	 as well as any "misstatement as to the quantity	 description or value of such goods on the part of the owner" as causes of short levy. Rule 10 A would appear to cover any "deficiency in duty if the duty has for any reason been short levied"	 except that it would be outside the purview of Rule 10A if its collection is expressly provided for by any Rule. Both the rules	 as they stood at the relevant time	 dealt with collection and not with assessment. They have to be harmonised	 In N. B. Sanjana 's case (Supra)	 this Court harmonised them by indicating that Rule 10A	 which was residuary in character	 would be inapplicable if a case fell within a specified category of cases mentioned in Rule 10. It was pointed out in Sanjana 's case (Supra). that the reason for the addition of the new Rule 10A was a decision of the Nagpur High Court in Chhotabhai Jethabhai Patel vs Union of India(1)	 so that a fresh demand may be made on a basis altered by law. The Excise authorities had then made a fresh demand	 under the provisions of Rule 10 A	 after the addition of that Rule	 the validity of which challenged but upheld by a Full. Bench of the High Court of Nagpur. This Court	 in Chhotabhai Jethabhai Patel & Co.	 vs Union of India ( 2 ) also rejected the assessee 's claim that Rule 10 A was inapplicable after pointing out that the new rule had been specifically designed" for the enforcement of the demand like the one arising in the circumstances of the case". We think that Rule 10 should be confined to cases where the demand is being made for a short levy caused wholly by one of the reasons given in that rule so that an assessment has to be reopened. The findings given by the Calcutta High Court do not show that	 in the case before us	 there was either a short levy or that one of the grounds for a short levy given in Rule 10 really and definitely existed. No doubt the Division Bench gave a reason for the way in which the claims became time barred	 in the following words: "It is quite possible	 that the Excise authorities	 in an attempt tohelp the	 appellants	 by facilitating the movements of goods	 inadvertently allowed the claims to be barred by limitation. That	 however	 is not a matter which can affect the question of limitation. The bar of limitation has been imposed by Statute. The morality of the case or the conduct of the parties is therefore irrelevant unless the law provides that the court on that ground can afford relief ' (1) A.I.R	 1952 Nag. 139	 (2) [1962] Supp. 2 S.C.R. 1 838 This finding was presumably given to show that the impugned notice fell within the purview of Rule 10 because the demand was due to a short levy caused by "inadvertence" of the officer concerned. It will be noticed that the Division Bench did not go beyond finding a "possibility" of such inadvertence. This is not a finding that it was definitely du. 	 to it. No finding which could clearly relate the	 case to any cause for short levy found in Rule 10 was given. Moreover	 we find that there was no case taken up by the Company in its petition before the High Court that any short levy resulted from an inadvertence. of the officer concerned in the process of assessment. The case set up was that of a levy after a completed assessment	 in accordance with law	 which could not	 according to the Company	 be reopened. If	 therefore	 as we find from the conclusions recorded by the High Court itself what took place was not an "asseessment" at all in the eye of law	 which could not be reopened outside the provisions of Rule 10	 we think that the case will fall beyond Rule 10 as it stood at the relevant time. The notice set out above does not purpoe	 to be issued under any particular rule probably because the Collector	. in the circumstances of the case	 was not certain about the rule under which the notice could fall. But	 as was pointed out by this Court in Sanjana 's case (Supra)	 the failure to specify the provision under which a notice is sent would not invalidate it if the power to issue such a notice was there. The notice alleges that it is a case of "incomplete assess ment". The allegations contained in it have been characterised by the learned counsel for the Company as a change of front intended to cover up the neglet of the Collector in failing to comply with the correct procedure of making either an assessment before delievery contemplated by Rule 52 or a provisional assessment under Rule 10 B. We are unable to hold	 either upon the findings given by the High Court or upon facts transpiring from the affidavits filed by the parties that the notice was a mere cloak for some omission or error or inadvertence of the Collector in making a levy or an assessment. We may point out that Rule 10 itself has been amended and made more reasonable in 1969 so as to require a quasi judicial procedure by serving a show cause notice "within 3 months from the date on which the duty or charge was paid or adjusted in the owner 's account current	 if any". This amendment	 made on 11 10 1969	 indicates that the quasi judicial procedure. for a finding on an alleged inadvertence	 error	 collusion	 or misconstruction by an officer	 or misstatement by the assessee	 as the cause of an alleged short levy resulting from an assessment	 can now be embarked upon and not necessarily completed 839 within the prescribed period. We are	 however	 concerned with the procedure before this amendment took place. At that time	 it was certainly not clear whether a case would fall under Rule 10 even before the short levy or its cause was established. Furthermore	 in the present case	 the reason for an alleged short levy could be a change of basis of proposed assessment under instructions from higher authorities mentioned above. Even that change of basis was held by the High Court to be erroneous. Until the High Court indicated the correct basis there was an uncertainty about it. Such a ground for an alleged short levy would be analogous to the reason for the introduction of Rule 10 A itself _ which	 as pointed out in N. B. Sanjana 's case (Supra)	 was 'a change in the law. One could go back still further and come to the conclusion that the real reason '	or the alleged short levy was a failure of the Company to supply the fuller information it used to supply previously and not just a misstatement. If the case does not clearly come within the classes specified in Rule 10	 this rule should not be invoked because	 as was rightly contended for the appellant	 a too wide construction put on Rule 10 would make Rule 10A useless. The two rules have to be read together. It is true that Rule 10 A seems to deal only with collection and not with the ascertainment of any deficiency in duty or its cause by a quasi judicial procedure. If	 however	 it is read in conjunction with Section 4 of the Act	 we think that a quasi judicial proceeding	 in the circumstances of such a case	 could take place under an implied power. It is well established rule of construction that a power to do something essential for the proper and effectual performance of the work which the statute has in contemplation may be implied [See Craies on Statute Law (Fifth Edition) P. 105] The question whether there was or was not an implied power to hold an enquiry in the circumstances of the case before us	 in view of the Provisions of Section 4 of the Act read with Rule 10 A of the	 Central Excise Rule	 was not examined by the Calcutta High Court because it erroneously shut out consideration of the meaning and applicability of Rule 10A. The High Court 's view was based on an application of the rule of construction that where a mode of performing a duty is laid down by law it must be performed in that mode or not at all. This rule flows from the maxim : "Expressio unius act exclusio alterius. " But	 as we pointed out by Wills	 J.	 in Colquohoun vs Brooks(1) this maxim "is often a valuable servant	 but a dangerous master . ". The rule is subservient to the basic principle that Courts must endeavour to ascertain the legislative intent and (1) (1888) 2 	62. 840 purpose	 and then adopt a rule of construction which effectuates rather than one that may defeat these. Moreover the rule of prohibition by necessary implication could be applied only where a specified procedure is laid down for the performance of. a duty. Although Rule 52 makes an assessment obligatory before goods are removed by a manufacturer	 yet	 neither that rule nor any other rule	 as already indicated above	 has specified the detailed procedure for an assessment. There is no express pro hibition anywhere against an assessment at any other time in the circumstances of a case like the one before us where no " assessment"	 as it is understood in law	 took place at all. On the other hand	 Rule 10A indicates that there are residuary powers of making a demand in special circumstances not foreseen by the framers of the Act or the rules. If the assessee disputes the correctness of the demand an assessment becomes necessary to protect the interests of the assessee. A case like the one before us falls more properly within the residuary class of unforeseen cases. We think that	 from the provisions of Section 4 of the Act read with Rule 10A	 an implied power to carry out or complete an assessment	 not specifically provided for by the rules	 can be inferred. No writs of prohibition or mandamus "	ere	 therefore	 called for in the circumstances of the case. Consequently	 we allow this appeal and set aside the orders of the Calcutta High Court. The Collector may now proceed to complete the assessment. In the circumstances of the case	 the parties will bear their own costs throughout.

The respondent manufactures cigarettes at its factory upon which Excise Duty is levied by the Assistant Collector of Central Excise	 Calcutta Division. The rates varied according to the provisions of Finance Act	 1951	 and 1956 and the Additional Duty of Excise (Goods of Special Importance) Act	 1957. The Company was required to furnish quarterly consolidated price lists and the particulars of cigarettes to be cleared were furnished by the Company as required by Rule 9 of the Central Excise Rules. For facilitating collection of duty	 the Company maintained a large sum of money in a Current Account with the Central Excise authorities	 who used to debit this account for the duty leviable on each stock of cigarettes allowed to be removed. The Company used	 to furnish its quarterly price lists to the Collector 	on forms containing nine columns and until July 1957	 so long as this form was used by the Company	 no difficulty was experienced in checking prices. But after this column was dropped from the new form of six	 columns	 the Excise authorities encountered some difficulty in valuing the cigarettes for levying Excise Duty. They therefore	 changed the basis of assessment from the Distributors selling price to the wholesale cash selling price at which stockists or agents were selling the same in the open market. The authorities informed the Company of this change of basis on 5 11 58 by letter	 which also asked the Company to furnish its price lists immediately for determining the correct assessable value of its cigarettes. Two days thereafter	 the authorities served a notice upon the Company demanding payment of Rs. 1	67	072	40 P. as Basic Central Excise Duty and Rs. 74	574	85 P. as Additional Central Excise Duty on ground of short levy for a certain brand of cigarettes cleared from Company 's Factory between 10th August 1958	 After another five days	 the authorities sent another notice demanding more than Rs. 6 lakhs as Basic Central Excise Duty and more than Rs. 2 lakhs as Additional Central Excise Duty. On the following day	 the authorities sent a third notice under Rule 10 A of the Central Excise Rules	 demanding more than Rs. 40	000/as Central Excise Duty and more than Rs. 16	000/ as Additional Duty. The Company challenged these notices by a writ before the High Court. 	 The High Court quashed the notices on the ground that the Company had not been given an opportunity of being heard. No appeal was filed by the other side against this decision	 but when the case went back to the Collector	 he issued P. fresh notice on 24 4 1960. By this notice	 for certain periods	 a sum of more than Rs. 10 lakhs was levied as Basic Central Excise Duty and a total sum of more than Rs. 3 lakhs as Additional Duty	 and this amount had been provisionally debited in the Company 's Account on the basis of the price list supplied by the Company and the Company was informed that if it desired a personal hearing	 it 823 can appear before the authorities to make the final assessment in accordance with law. The Company challenged the validity of this notice dated 24 4 60 on the ground that the notice was barred by limitation and was 'issued without jurisdiction	 so that no proceedings could be taken. The learned single Judge	 as well as the Divisional Bench of the High Court allowed the petition on the ground that the notice was barred by time under Rule 10 of the Central Excise Rules because the notice was held to be fully covered by Rule 10 and by no other rule. The case was certified under article 33(a)	 (b) and (d) for an appeal to this Court. Rule 10 of the Central Excise Rules provides that when duties or charges have been short levied through inadvertence or misconstruction etc.	 the person chargeable with the duty so short levied	 shall pay the deficiency or pay the amount paid to him in excess on written demand by the proper officer within three months from the date on which the duty or charge is paid or adjusted in the owner 's account	 if any	 or from the date of making the refund. It was contended that this was substantially a provisional assessment covered by Rule 10 B. The Division Bench of the High Court	 however	 refused to agree that the impugned notice of 24 460 fell under Rule	 10 A. The reason given for this refusal was that such a case was neither taken before the learned single Judge	 nor could be found in the grounds	 of the appeal despite the fact that the appellant had ample opportunity of amending its Memorandum of Appeal. Allowing the appeal. HELD : (i.) That the High Court erroneously refused to consider whether the impugned notice fell under Rule 10 A. The applicability of Rule 10 A was very much in issue because the Collector in his affidavit denied that Rule 10 A of the said rules had any application to the facts of the case. (ii) It cannot be accepted that merely because the current account kept under Rule 9 indicated that an accounting had taken place	 there was necessarily a legally valid or complete levy. The making of debit entries was only on ground of collection of the tax. Even if payment or actual collection of tax could be spoken of as a defective levy	 it was only provisional and not fINal. It could only be closed or invested with validity after carrying out the obligation to make an assessment that really determines whether the levy is short or complete. It is not a faCtual or presumed levy which could prove an assessment. This has to be done by proof of the actual steps taken which constitute assessment. [836D] A mechanical adjustment	 or settlement of accounts by making debit entries was gone through in the present case	 but it cannot be said that any such adjustment is assessment which is a quasi judicial process and involves due application of mind to the facts	 as well as to the requirements of law. Rule 10 and 10 A seems to be so widely worded as to cover any inadvertence error etc.; whereas Rule 10 A would appear to cover any deficiency in duty if the duty has for any reason	 been short levied	 except that it would be outside the purview of Rule 10 A if its collection is expressly provided or by any rule. Both the rules as they stood at the relevant time	 deal with collection	 and not with assessment. In N. B. Sanjana 's case ; this Court indicated that Rule 10 A which was residual. in character	 would be inapplicable if a case fell within a specified category of cases mentioned in Rule 10. It was pointed out in Sanjana 's case that the reason for the addition 824 of the new rule 10 A was a decision of the Nagpur (Chotabhai Jethabhai 's case; A.I.R. 1952 Nagpur 139)	 so that a fresh demand may be made on a basis altered by law. The excise authorities had made a fresh demand under Rule 10 A	 the validity of which was challenged	 but it was upheld by a Full Bench decision of the High Court of Nagpur. This Court	 in Chotabhai Jethabhai 's case also rejected the assessee 's claim that Rule 10 A was inapplicable after pointing out that the new rule was specifically designed for the enforcement of the demand like the present one. [836F 837E] (iii)The present case	 therefore	 falls within the residuary clause of unforeseen cases from the provisions of section 4 of the Act	 read with Rule 10 A	 an implied power to carry out or complete an assessment	 not specifically provided for by the rules	 can be inferred. Therefore	 it is wrong to hold that the case falls under Rule 10 and not under Rule 10 A.