Summarize the following court judgment. Appeals Nos. 511 514 of 1966. Appeals	 by special leave from the judgments and orders dated August 9	 1961	 July 20	 1964	 of the Bombay High Court	 Nagpur Bench in Misc. Civil Applications Nos. 1118 of 1959. 192 of 1961. 1360 of 1959 and 193 of 1961 respectively. H. R. Gokhale	 M. R. Bhandare	 P. C. Bharta	 and O. C. Mathur	 for the appellant (in all the appeals). N. section Bindra	 P. C. Chatterjee	 section P. Nayar for R.H. Dhebar	 the respondents (in all the appeals). The Judgment of WANCHOO C. J.	 MITTER and HEGDE	 JJ. was delivered by HEGDE	 J. The dissenting judgment of BACHAWAT and RAMASWAMI	 JJ. was delivered by BACHAWAT	 J. HEGDE	 J. The principal question canvassed in this group of appeals by special leave is whether section 11(4)(a) of the Central Provinces and Berar Sales Tax Act 1947	 to be referred to as the Act hereinafter	 is ultra vires Article 14 of the Constitution and consequently the notices impugned in the writ petitions from which these appeals arise are liable to be struck down and the respondents restrained from levying sales tax on the appellants for the period May 1	 1952 to October 31	 1955. The appellants are a private limited company carrying on business inter alia as dealers in iron and steel materials in Vidharba region of the Maharashtra State. In that region they have more than one place of business. They registered themselves as dealers under section 8A of the Act and obtained a certificate of registration on August	 17	 1947. Their assessment year as shown in their registration certificate is from November 1 to October 31. They were required to submit quarterly returns of their turnovers. They did so till April 30	 1952. Thereafter no returns were submitted. On September 13	 1955	 the Assistant Commissioner of Sales Tax	 the assessing authority at that time	 issued a notice calling upon the appellants to show cause why action should not be taken against them under sections 10(3) and 11(4)(a)	 on account of their failure to furnish the return for the period 1.1.53 to 31.12.53. Similar notices were issued to them on October 27	 1955 for the period 1.1.54 to 31.12.54 and on July 7	 1956 for the period 1.1.55 to 31.12.55. It appears that the appellants repeatedly took time for submitting their explanation. The first respondent to whom the appellants ' case stood transferred issued in 1958 fresh notices to the appellants similar to those issued in 1955. At that stage the appellants objected to the validity of those notices both orally as well as in writing on the ground that their assessment year was not the calendar year as mentioned in those notices but the year ending October 31. Evidently in view of that objection	 the first respon dent issued another set of notices on July 8	 '1959. The appellants contended that those notices were barred by time. Thereafter the appellants challenged the validity of the notices issued in 1959 in the petitions under article 226 from which these appeals arise. In these apneals the questions arising for decision are whether section 11 (4)(a) or section 11 A(3) or any parts thereof contravene the guarantee of equal protection of the laws or equality before the law or whether those provisions are based on a valid classification which is reasonable in view of the object with which they were enacted. Mr. H.R. Gokhale learned counsel for the appellants	 urged that both these provisions deal with the same class of persons having common characteristics and Properties and hence there is no just 666 basis for the classification made. According to him the classification complained of has brought about a discrimination. Further he asserted that the Act had conferred arbitrary power on the assessing authority to pick and choose from the persons belonging to the same class to be dealt with either under section 11(4)(a) or under 11A(1). He urged that as a case coming under section 11(4)(a) also falls under section 11 A	 as the law now stands	 the persons proceeded against under section 11A(1) will have the benefit of the period of limitation prescribed therein; while the said benefit is not available for those proceeded under section 11(4)(a). According to the learned counsel for the revenue	 sections 11(4)(a) and 11A deal with different classes of persons; the classification made under those provisions is a reasonable classification having nexus with the object sought to be achieved. Before adverting to the points at issue	 it would be convenient to set out the circumstances under which section 11A(3) which is said to have brought about the discrimination complained of came to be enacted. The Act is in force ever since 1947. Section 11A as it originally stood was inserted into the Act in 1953. In Bisesar House vs State of Bombay(1) the question arose whether a notice under section 11(2) initiates a fresh proceeding and if that is so	 whether the limitation prescribed under s.11A(1) is attracted to that proceeding. A Full Bench of the Bombay High Court speaking through Chagla	 C. J. held that a notice under section 11(2) initiates a fresh proceeding and to such a proceeding the limitation prescribed in section 11A is attracted. From the ratio of that decision it followed that the limitation prescribed under section 11 A also governed proceedings under s.11(4)(a). Evidently	 to get over the effect of that decision	 the Bombay Legislature enacted the Bombay Sales Tax Laws (Validating Provisions and Amendment) Act 1959 (No. 22 of 1959) which came into force on April 18	 1959. Section 6 of that Act inserted the new subsection (3) into S.11A and the reason for that amendment	 as stated in the statement of objects and reasons	 is as follows: "In its judgment in Bisesar House vs Commissioner of Sales Tax	 Nagpur	 the Bombay High Court has held that the period of limitation laid down in S.IIA of the Central Provinces and Berar Sales Tax Act	 1947	 for reassessment of the turnover which has escaped assessment applies to original assessment also. It has also been found that the said limitation applies to suo motu revisions also. The said decision affects the original assess ments and suo motu revisions	 which have been made after the expiry of the period of limitation laid down for the reassessment of turnover escaping assessment under the different sales tax laws in force in this State. It has	 (1) 60 B.L.R. 1395 667 therefore	 become necessary to establish the validity of all such assessments and to provide that the period of limitation prescribed for reassessment of escaped turn overs does not apply to original assessment and suo motu revisions. " In Ghanshyam Das vs Regional Assistant Commissioner of Sales Tax	 Nagpur(1) this Court did not agree with that decision so far as the scope of s.11(2) is concerned. Therein it was held that a notice under section 11(2) does not initiate a fresh proceeding and to that proceeding the limitation prescribed in section 11A does not apply. Though in view of that decision	 s.11A(3) became superfluous in respect of a proceeding in which a notice under section 11 (2) is given	 it undoubtedly changed the law in respect of proceedings under s.11(4)(a). Before we proceed to consider the aforementioned complaint of discrimination	 it is necessary to have a survey of the relevant provisions of the Act. 'Dealer ' is defined in section 2(c) as meaning a person who whether as principal or agent carries on in the State the business of selling or supplying goods whether for commission	 remuneration or otherwise and includes a firm	 a partnership	 a Hindu undivided family or a State government or any of their departments and includes also a society	 club or association selling or supplying goods to its members. A 'registered dealer ' is defined in section 2(f) as meaning a dealer registered under the Act. Section 2(j) defines 'turnover ' as meaning the aggregate of the amounts of sale prices and parts of sale prices received or receivable by a dealer in respect of the sale or supply of goods or in respect of the sale or supply of goods in the carrying out of any contract effected or made during the prescribed period; and the expression 'taxable turnover ' means that part 'of a dealer 's turnover during such period which remains after deducting therefrom his turnover during that period in respect of the sale of goods declared tax free under section 6 The definition of the term 'year ' as provided in section 2(1) to the extent necessary for our present purpose reads: "year ' means the 12 months ending on 31st day of March	 or if the accounts of the assessee are made up to any other day in respect of a year ending on any date other than the 31st day of March	 than at the option of the assessee the year ending on the day to which his accounts have been so made up. . . ." Section 8 says: "(1) No dealer shall	 while being liable to pay tax under this Act	 carry on business as a dealer unless he has been registered as such and possesses a registration certificate." Section 8A provides for voluntary registration of a dealer. Sub s.(3) thereof provides that every dealer who has been registered upon an application made under this section so long as his registration remains in force	 be liable to pay tax under that Act. Sub section(4) of that section stipulates that the registration of a dealer upon an application made under that section shall be in force for a period not less than three complete years and shall remain in force thereafter unless cancelled under the provisions of the Act. Section 10 provides for returns by dealers. It reads: "(1) Every such dealer as may be required so to do to by the Commissioner by notice served in the prescribe manner and every registered dealer shall furnish such returns by such dates and to such authority as may be prescribed." Sub section(2) of that section is not necessary for our present purpose. Sub section(3) of that section reads: "(3) it a dealer fails to comply with the requirement of a notice issued under sub section (1) or a registrate dealer fails to furnish his return for any period within prescribed time to the prescribed authority without any sufficient cause	 the Commissioner may	 after giving such dealer a reasonable opportunity of being heard	 direct him to pay	 by way of penalty	 a sum not exceeding one fourth of the amount of the tax which may be assesses on him under section 11 ". Sections 11 and 11A are important for our present purpose. They deal with assessment and assessment on turnover escaping assessment. They	 to the extent necessary for our present purpose read: "11(1).If the Commissioner is satisfied that the returns furnished by a dealer in respect of any period are correct and complete	 he shall assess the dealer on them	 (2) If the Commissioner is not so satisfied he shall serve the dealer with a notice appointing a place and day and directing him (i) to appear in person or by an agent entitled to appear in accordance with the provision of section 11B	 (ii) to produce evidence or have it produced in support of the returns or (iii) to produce or cause to be produced any accounts	 registers	 cash memoranda or other document	 as may be considered necessary by the Commissioner for the purpose	 (3) After hearing the dealer or his agent and examining the evidence produced in compliance with the requirements of clause (ii) or clause (iii) of sub section(2) and such further evidence as the Commissioner may be require	 the Commissioner shall assess him to tax. (4) If a registered dealer (a) does not furnish returns in respect of any period by the prescribed date or (b) having furnished such returns fails to comply with any of the terms of a notice issued under sub section (2)	 or (c) has not regularly employed any method of accounting or if the method employed is such that	 in the opinion of the Commissioner	 assessment cannot properly be made on the basis thereof	 the Commissioner shall in the prescribed manner assess the dealer to the best of his judgment: Provided that he shall not so assess him in respect of the default specified in clause (a) unless the dealer has been first given a reasonable opportunity of being heard." (Sub sections 5 and (6) are not necessary for our present purpose). Section 11A provides: "(1).If in consequence of any information which has come into possession	 the Commissioner is satisfied that any turnover of a dealer during any period has been under assessed or has escaped assessment or assessed at a lower rate or any deduction has been wrongly made therefrom	 the Commissioner may	 at any time within three calendar years from the expiry of such period	 after giving the dealer a reasonable opportunity of being heard and after making such enquiry as he considers necessary	 proceed in such manner as may be prescribed to reassess or assess	 as the case may be	 the tax payable on any such turnover; and the Commissioner may direct that the dealer shall pay	 by way of penalty in addition to the amount of tax so assessed	 a sum not exceeding that amount. The assessment or reassessment made under sub section (1) shall be at the rate at which it would have been made	 had there been no under assessment or escapement. Nothing in sub sections (1) and (2) (i) shall apply to any proceeding (including any notice issued) under Sections 11 or 22A or 22B	 and (ii) notwithstanding any judgment	 decree or order 'of a Court or Tribunal	 shall be deemed ever to have been applicable to such proceeding or notice. (b) The validity of any such proceeding or notice shall not be called in question merely on the ground that such proceeding or notice was inconsistent with the provisions of sub sections (1) and (2). Rule 19 of the rules framed under the Act provides that every registered dealer should furnish to the appropriate sales tax 670 officer his quarterly return in the prescribed form within one calendar month from the expiry of the quarter to which the return relates. Each of such returns submitted should be accompanied by a treasury challan in the form prescribed in proof of the fact that he had paid the tax payable on the basis of his return	 The only other rule relevant for Our present purpose is r. 32 in Part VII of the Rules	 which deals with assessment of tax and/ or penalty. That rule provides that where a registered dealer has rendered himself to a best judgment assessment as well as penalty by reason of his default in furnishing the prescribed return or re turns in respect of any period by the prescribed date	 the assessing authority shall serve on him a notice in form 12 specifying the default	 escapement or concealment as the case may be and calling upon him to show cause by such date ordinarily not less than 30 days	 from the date of issue of the notice	 as may be fixed in that behalf	 why he should not be assessed or reassessed to tax	 or a penalty should not be imposed upon him and directing him lo produce on the said date his books of account and other documents which the assessing authority may require or which he may wish to produce in support of his objection. That rule further pro vides that no such notice shall be necessary where the dealer	 having appeared before the assessing authority	 waives such notice. Now we may turn to the questions formulated for decision. As mentioned earlier	 the main contention advanced on behalf of the appellants is that sub section(3) of section 11A has brought about a discrimination between those dealers proceeded against under section 11(4)(a) and those dealt with under section 11A. The contention advanced on behalf of the appellants is that the turnover of a registered dealer who has failed to submit his return and also to deposit the tax due from him	 has escaped assessment; the case of such a dealer comes both within section 1 1 (4) (a) as well as section 11A; therefore	 he can be dealt with under either of those two provisions. Where section 11A prescribes a period of limitation for a proceeding under that provision	 in view of sub section 3 of section 11A a proceeding under section 11(4)(a) can be initiated at any time; under those circumstances it is open to the authorities to proceed against some of the same class of dealers under section 11(4)(a) and others under section 11A. It was said on their behalf that it is well settled that in its application to legal proceedings	 article 14 assures to every one the same rules of evidence and modes of procedure; in other words	 the same rule must exist for all in similar circumstances. On the other hand	 it was urged on behalf of the revenue that section 11(4)(a) deals only with registered dealers who have certain advantages under the Act	 whereas section 11A deals with dealers who do not come either under section 11(4) or section 11(5)	 and therefore the classification of dealers made under the various provisions is based on real and substantial distinction bearing a just and reasonable relation to the object sought to be attained. 671 We have now to see whether the dealers who come within the mischief of section 11(4)(a) can also be dealt with under section 11A. Before a person can be dealt with under section 11A	 it must be shown that in consequence of any information which has come into his possession	 the Commissioner is satisfied that any turnover of that dealer during any period has been under assessed or has escaped assessment or assessed at a lower rate or any deduction has been wrongly made therefrom. Quite plainly the expression 'dealer ' in section IIA(1) includes both registered and unregistered dealers. In this case we are concerned with the escapement of assessment. Therefore the first question that arises for decision is whether it can be said that the appellants ' turnovers for the period 1 5 52 to 30 10 55 had escaped assessment. There is no dispute that those turnovers had not been assessed. From the fact that those turnovers had not been assessed	 can it be said that they had escaped assessment? In Maharaj Kumar Kamal Singh vs Commissioner of Income Tax	 Bihar and Orissa	(1)	 this Court laid down that the expression "has escaped assessment" in section 34(1)(b) of the Indian Income Tax Act	 1922 is applicable not only where the income has not been assessed owing to inadvertence or oversight or owing to the fact that no return has been submitted	 but also where a return has been submitted but the income tax officer erroneously failed to tax a part of assessable income. In Commissioner of Income Tax	 Bombay City vs M/s. Narsee Nagsee and Co.	 Bombay(2) interpreting the words "profits escaping assessment" in section 14 of the Business Profits Tax Act	 1947	 this Court held that those words apply equally to cases where a notice was received by the assessee but resulted in no assessment	 under assessment or excessive relief and to cases where due to any reason no notice was issued to the assessee and there was no assessment of his income. Kapur	 J. speaking for the majority of Judges in that case	 observed (at p. 993 of the report) that it is well settled that an income escapes assessment when the process of assessment has not been initiated as also in a case where it has resulted in no assessment after the completion of the process of assessment. The true scope of the expression "escaped assessment" in section 11A came up for consideration before this Court in Ghanshyam Das vs Regional Assistant Commissioner of Sales Tax	 Nagpur(3). This is what Subba Rao	 J. (as he then was) who delivered the judgment of the majority of the Judges	 observed in that regard: "In Commissioner of Income Tax	 Bombay vs Pirojbai N. Contractor the words 'escaped assessment ' in the Indian Income tax Act were defined. It was held therein that the said words were wide enough to include cases where no notice under s.22(2) of the Income tax Act had been issued to the assessee and therefore his income had not been assessed at all under section 23 thereof. The said view has been assumed to be correct by this Court in Maharaj Kumar Kamal Singh vs Commissioner of Income Tax	 Bihar and Orissa [1959] Supp. 1 S.C.R. 10 and Maharajadhiraj Sir Kameshwar Singh vs State of Bihar ([1960] 1 S.C.R. 322) and extended to cover a	 case where the first assessment was made in due course but a part of the income escaped therefrom. This Court	 in Commissioner of Income tax	 Bombay vs Narsee Nagsee and Co. ([1960] 3 S.C.R. 988)	 construing the provisions of section 14 of the Business Profits Tax Act	 1947	 reviewed the law on the subject and came to the following conclusion: All these cases show that the words "escaping assessment" apply equally to cases where a notice was received by the assessee but resulted in no assessment at all and to cases where due to any reason no notice was issued to the assessee	 and	 therefore	 there was no assessment of his income. ' It is true that the said decisions were given with reference to either section 34(1) of the Income Tax Act or section 14 of the Business Profits Tax Act but so far as the present enquiry is concerned the said sections are in pari materia with section 11A of the Act. In construing the meaning of the expression 'escaped assessment ' in section 11A of the Act there is no reason why the said expression should bear a more limited meaning than what it bears under the said two Acts. All the three Acts are taxing statutes and the three relevent sections therein are intended to gather the revenue which has improperly escaped. A division Bench of the Madras High Court in the State of Madras vs Balu Chettiar (7 S.T.C. 519) following the decision of a Full Bench of that Court	 held that where an assessee did not tile at any time a return of his turnover for a year and	 therefore	 there was no assessment made	 the turnover escaped assessment. It was observed therein: 'Whether it was a case of omission or of deliberate concealment on the part of the assessee	 he did not submit any return. It was his default that led to the escape of the turnover for 1951 52 from assessment to the tax lawfully due. It was the whole of the turnover for that year that escaped assessment. ' It is not necessary to multiply citations. We	 therefore	 hold that the expression 'escaped assessment ' in section 11A of the Act includes that of a turnover which has not been assessed at all	 because for one reason or other no assess ment proceedings were initiated and therefore no assessment was made in respect thereof." In one of the appeals dealt with in that judgment	 i.e. C.A. No. 102 of 1901	 this Court had to consider whether a case under 673 (a) also comes under section 11A. The Court answered that question in the affirmative seen earlier it was the duty of the appellants not only to submit their quarterly returns but send along with those returns the treasury challans in proof of the payment of the tax admittedly due from them. As they have failed to do so within the prescribed period	 it follows that the turnovers in question had escaped assessment. This takes us to	 the next question whether in the instant case the assessing authority can be said to have been satisfied about the escapement of the assessment as a consequence of any information which had come into his possession. From the notices issued in 1955 as well as later on	 it is clear that the assessing authorities were satisfied about the escapement of the assessment due from the appellants. But the real question is whether they were so satisfied "in consequence of any information which had come into their possession". The assessing authorities knew that the appellants had neither submitted their returns nor treasury challans in proof of the payment of the tax due from them. From that circumstance it is reasonable to	 hold that in consequence of the information that the appellants had not submitted their returns as well as the treasury challans the assessing authority should have been stisfied about the escapement of the assessment. It was urged on behalf of the revenue that 'information ' contemplated by s.11A should be from some outside source and not something that could be gathered by the assessing authority from his own records. According to the revenue in the instant case there was no information from any outside source	 therefore	 it cannot be said that the assessing authority was satisfied about the escapement of tax in consequence of any information which has come into its possession. In our view	 this contention is untenable. In Maharaj Kumar Kamal Singh vs Commissioner of Income Tax	 Bihar and Orissa	 this Court held that the word 'information ' in section 34(1)(b) of the Income Tax Act	 1922	 includes information as to the true and correct state of the law and so would cover information as to the relevant judicial decisions. It was laid down therein that that information need not be about any fact; it may be even as to the legal position. In other words	 the term 'information ' in section 34(1)(b) of the Income Tax Act 1922 really means knowledge. In Salem Provident Fund Society Ltd. vs Commissioner of Income Tax madras(1) a division bench of the Madras High Court interpreting the scope of the words 'information which has come into his possession ' found in section 34 of the Indian Income Tax Act	 observed thus: "We are unable to accept the extreme proposition that nothing that can be found in the record of the (1) 674 assessment which itself would show escape of assessment or under assessment	 can be viewed as information which led to the belief that there has been escape from assessment or under assessment. Suppose a mistake in the original order of assessment is not discovered by the Income Tax Officer himself on further scrutiny but it is brought to his notice by another assessee or even by a subordinate or a superior officer	 that would appear to be information disclosed to the Income Tax Officer. If the mistake itself is not extraneous to the record and the informant gathered the information from the record	 the immediate source of information to the Income	 Tax Officer in such circumstances is in one sense extraneous to the record. It is difficult to accept the position that while what is seen by another in the record is 'information ' what is seen by the Income Tax officer himself is not information to him. In the latter case he just informs himself. It will be information in his possession within the meaning of section 34. In such cases of obvious mistakes apparent on the face of the record of assessment	 that record itself can be a source of information	 if that informa tion leads to a discovery or belief that there has been an escape of assessment or under assessment." The meaning of the word 'information ' came up again for consideration before a division bench of the Kerala High Court in United Mercantile Co. Ltd. vs Commissioner of Income Tax Kerala(1). Their Lordships held that to 'inform ' means to 'impart knowledge ' and a detail available to the Income Tax Officer in the papers filed before him does not by its mere availability become an item of 'information '. It is transmuted into an item of information in his possession only if and when its existence is realised and its implications recognized. Applying that test to the facts of the case before them the Court held that the awareness of the Income Tax Officer for the first time after the assessment order of November 19	 1957	 that the bonus shares were issued not out of Premiums received in cash and the consequent result in the light of the Finance Act 1957	 was information within the meaning of that expression as used in section 34(1) of	the Indian Income Tax Act	 1922	 and consequently the reopening of the assessment under that provision was not illegal. In our judgment	 the knowledge of the fact that the appellants had not submitted their quarterly returns as well as the treasury challans. constituted In information to the assessing authority from which it could be satisfied and in fact it was satisfied that the turnovers with which we are concerned in this case bad escaped assessment. (1) 675 From the above conclusions it follows that the appellants ' case falls both under section 11(4)(a) and section 11A(1). Therefore	 it was open to the assessing authority to proceed against them under any one of those two sections. But as they were proceeded against under section 11(4)(a) they cannot have the benefit of the period of limitation prescribed under section 11 A(1). Hence	 it must be held that the present case falls within the rule laid down by this Court in Suraj Mail Mohta and Co. vs A. V. Visvanatha Sastri & another(1). On the facts found it follows that section 1 (4)(a) has become a discriminatory provision in view of section 11 A(3). Hence the same is liable to be struck down under article 14. But for the inclusion of sub section 3 in section 11A	 there would have been no discrimination between those dealt with under section 11(4)(a) and those under section 11A(1). The period of limitation prescribed in section 11A(1) would have attracted itself to proceedings under section 11(4)(a) as held by this Court in Ghanshyam Das 's case(2). Mr. Bindra	 learned counsel for the revenue	 contended that a registered dealer has certain advantages over an unregistered dealer; therefore the classification made under the Act is a reasonable classification. To be a valid classification	 the same must not only be founded on an intelligible differentia which distinguishes persons and things that are grouped together from others left out of the group but that differentia must have a reasonable relation to the object sought to he achieved. Both section 11(4)(a) and section 11A(1) concern themselves with escaped assessments. The classification suggested has no nexus with that object. That much is established by the decision of this Court in Ghanshyam Das 's case(1) which is binding on us. It is true the State can by classification determine who should be regarded as a class for the purpose of legislation and in relation to a law enacted on a particular subject	 but the classification must be based on some real and substantial distinction bearing a just and reasonable relation to the object sought to be attained and cannot be made arbitrarily and without any substantial basis. Judged from the object sought to be achieved by the Act	 we are of the opinion that the classification made between the registered and unregistered dealers is not a reasonable classification. From this conclusion it follows that section 11(4)(a) is liable to he struck down as being discriminatory in view of section 11A(3). Section 11(4)(a) is separable from the rest of the sub section. Its separation from that sub section does not affect the implementation of the other provisions of the Act. This takes us to the question which was debated at our in stance whether the notices issued by the assessing authority in 1955 were valid notices. The High Court had not considered this question	 though it appears that the same was presented to it for decision (1) ; 	 (2) ; L/P(N)7SCI 4 676 by the parties. In the course of its judgment	 the High Court observed: "In this view (in view of its earlier findings) of the matter it is not necessary to consider whether the earlier notices of the year 1955 are good and valid notices or whether they stood superseded by subsequent notices of 1958 and 1959". For convenience we shall take up for consideration notice No. 4519/STN dated 13 9 55. Our conclusions in respect of that notice would cover the other notices. The material facts as set out by the High Court	 the correctness of which was not disputed before us	 are these: "On the 3rd September	 1955	 the Assistant Commissioner	 Sales Tax	 issued a notice under section 10(3)	 section 11(4) (a)	 section 11A and sub section(1) of section 22C of the Act	 calling upon the petitioners to show cause why action should not be taken against them under section 10(3) and section 11(4) of the Act on account of their failure to furnish the returns for the period 1 1 53 to 31 12 53. Similar notices were given on 27th October	 1955 for the period 1 1 54 to 31 12 54 and on 7th July 1956 for the period 1 1 55 to 31 12 55. From those facts	 it is seen that no notice had been issued within three years in respect of the turnover relating to the period from 1 5 52 to 31 12 52. The assessment in respect of that period is clearly barred in view of our earlier conclusion. The period 1 1 1 52 to 31 1 53 forms part of the quarter commencing from 1 11 52. No notice was given in respect of that quarter. A quarter forms a unit by itself. Therefore	 it follows that the proceeding in respect of that quarter is also barred by limitation. Now we shall take up the question whether the notices issued in 1955 in respect of the turnovers relating to other quarters were in accordance with law. The notice No. 4519/STN dated 13 9 55 reads."Notice (for 1 1 53 to 31 12 53) dated 13 9 55.No. 4519/ STN.D/13 9 55. Form XII (See rule 32) Notice under sub section (3) of section 10	 sub section (4) (a) and (5) of section 11	 sub section (1) of section 11 (A) and sub section (1) of section 22 of the Central Provinces and B erar Sales Tax Act	 1947. Whereas Shri Anandji Haridas and Co.	 Ltd.	 Nagpur. You have failed to furnish a return as required by a 677 notice in that behalf served on you under section 10(1) of the Central Provinces and Berar Sales Tax Act	 1947. OR You being a registered dealer have failed to furnish a return for the periods 1 1 53 to 31 12 53 and have thereby rendered yourself liable under section 11 (4) to be assessed to the best of judgment; Further	 you are hereby directed to attend in person or by a person authorised by you in writing in that behalf	 being a person specified in section 11B(1) before me and to produce or cause to be produced your books of accounts and the documents specified in the schedule hereunder and any evidence on which you rely in support of your objection at Jabalpur at 11 00 A.M. on 22 9 55. Sd/ Asstt. Commissioner of Sales Tax Nagpur Region	 Nagpur." It is true that it is not a notice in respect of any particular quarter	 it is a notice in respect of the period 1 1 53 to 31 12 53. In the State of Orissa and another vs M/s. Chakobhai Chelabhai and Company	(1) this Court held that the issue of one notice under section 12(5) of the Orissa Sales Tax Act	 1947 which section is similar to section 11(4)(a)	 for several quarters was not contrary to law as the section makes reference to a period which might consist of more than one quarter. From the notice in question it cannot be made out whether the assessing authorities wanted to deal with the appellants under section 10(1) or under section 11(4). The notice says that the appellants "had failed to furnish the return as required by a notice in that behalf served on them under section 10(1) of the Act	 or that they being registered dealers had failed to furnish return for the periods mentioned therein and thereby rendered themselves liable under section 11(4) to be assessed to the best of judgments Quite dearly	 the first alternative mentioned in the notice did not apply to the appellants. They are registered dealers. No notice under section 10(1) had been given to them. The assessing authority by mistake had failed to strike out the first alternative shown in the printed form. That circumstance could not have prejudiced the appellants. It was held by this Court in Chakobai Chelabhai 's case(1) referred to earlier that such a mistake does not vitiate the notice issued. But the more serious mistake pointed out by Mr. Gokhale in that notice is that the assessment year mentioned in that notice is not the assessment year of the 'appellants. Their assessment Years commenced from 1st November. This error according to Mr. Gokhale vitiated the notices issued. Yet another complaint made by Mr. Gokhale was that though r. 32 provides that ordinarily not less than 30 days notice should be given to the assessee	 only 9 days notice was given. But this defect was found only in the notice quoted above and not in the other notices issued in	1955. For the reasons to be mentioned presently	 we see no merit in either of these contentions. We are unable to accept the contention of Mr. Gokhale that a notice under section 11(4)(a) or 11A(1) is a condition precedent for initiating proceedings under those provisions or that it is the very foundation for the proceedings to be taken under those provisions. The notice contemplated under r. 32 is not similar to a notice to be issued under section 34(1)(b) of the Income Tax Act	 1922. All that sections 11(4) and 11A(1) prescribe is that before taking proceedings against an assessee under those provisions	 he should be given a reasonable opportunity of being heard. In fact	 those sections do not speak of any notice. But r. 32 prescribes the manner in which the reasonable opportunity contemplated by those provisions should be afforded to the assessee. The period of 30 days prescribed in r. 32 is not mandatory. The rule itself says that 'ordinarily ' not less than 30 days notice should be given. Therefore	 the only question to be decided is whether the defects noticed in those notices had prejudiced the appellants. It may be noted that when the assessees received the notices in question	 they appeared before the assessing authority	 but they did not object to the validity of those notices. They asked for time for submitting their explanation. The time asked for was given. Therefore	 the fact that only nine days were given to them for submitting explanation could not have in any manner prejudiced them far as the mistake in the notice as regards the assessment year is concerned	 the assessees kept silent about that circumstance till 1958. It was only when they were sure that the period of limitation prescribed by section 11A had expired hey brought that fact to the notice of the assessing authority. It is clear that the appellants were merely trying to take advantage of the mistakes that had crept into the notices. They cannot be permitted to do so. We fail to see why those notices are not valid in respect of the periods commencing from February 1	 1953 till 31 10 55. We are unable to agree with Mr. Gokhale 's contention that each one of those notices should	 be read separately and that we should not consider them together. If those notices are read together as we 'think they should be	 then it is clear that those notices give the appellants the reasonable opportunity contemplated by sections 11(4) '(a) and 11A(1). In Chatturain and Others vs Commissioner Pt 'Income Tax	 Bihar	(1) the: (1) 679 Federal Court held that any irregularity in issuing a notice under section 22 of the Income Tax Act	 1922 does not vitiate the proceeding that the income tax assessment proceedings commence with the issue of the notice	 but the issue or receipt of the notice is	 however	 not the foundation of the jurisdiction of the Income Tax Officer to make the assessment or of the liability of the assessee to pay the tax. The liability to pay the tax is :founded on sections 3 and 4 of the Income Tax Act which are the charging sections. Section 22 and others are the machinery sections to determine the amount of tax. The ratio of that decision applies to the facts of the present case. In our opinion	 the notices issued in the year 1955 are valid notices so far as they relate to the period commencing from February 1	 1953 to 31 10 55. In view of our conclusion that every escapement of assessment coming within the scope of section 11(4)(a) is also an escapement of assessment under section 11 A(1)	 a notice issued under section 11 (4)(a) would be a vaild notice in respect of a proceeding under section 11A(1). In the result	 we hold that the assessing authority has no competence to assess the turnovers of the appellants in respect of the quarters commencing from 1 5 52 and ending with January 31	 1953 as the same is barred by time under section 11A. We further hold that section 11(4)(a) is void as it is: violative of article 14. We accordingly issue a direction to the respondents to refrain from assessing the appellants in respect of those turn overs. In other respects	 the appeals fail and they are dismissed. In the circumstances of these cases	 we make no order as to costs. Bachawat	 J. Sections	 11(4)	 11(5) and 11 A of the C.P. and Berar Sales Tax Act	 1947 are as follows: "11(4) If a registered dealer (a) does not furnish returns in respect of any period by the prescribed date	 or (b) having furnished such ;return fails to comply with any of the terms of a notice issued under subsection (2)	 or (c) has not regularly employed any method of accounting	 or if the method employed is such that	 in the opinion of the Commissioner	 assessment cannot properly be made on the basis thereof	 the Commissioner shall in the	 prescribed manner assess the dealer to the best of his judgment: Provided that he shall not so assess him in respect of the default specified in clause (a) unless the dealer has been first given a reasonable opportunity of being beard. 680 (5) If upon information which has come into his possession	 the Commissioner is satisfied that any dealer has been liable to pay tax under this Act in respect of any period and has nevertheless wailfully failed to apply for registration	 the Commissioner shall	 at any time within three calendar years from the ex piry of such period	 after giving the dealer a reasonable opportunity of being heard	 proceed in such manner as may he prescribed to assess to the best of his judgment the amount of tax due from the dealer in respect of such period and all subsequent periods:and the Commissioner may direct that the dealer shall pay by way of penalty in addition to the amount of tax so assessed a sum not exceeding one and a half times that amount. 11 A. (1) If in consequence of any information which has come into his possession	 the Commissioner is satisfied that any turnover of a dealer during any period has been under assessed or has escaped assessment or assessed at a lower rate or any deduction has been wrongly made therefrom the Commissioner may	 at any time within three calendar years from the expiry of such period	 after giving the dealer a reasonable opportunity of being heard and after making such inquiry as he considers necessary	 proceed in such manner as may be prescribed to re assess or assess	 as the case may be	 the tax payable on any such turnover; and the Commissioner may direct that the dealer shall pay	 by way of penalty in ad dition to the amount of tax so assessed	 a sum not exceeding that amount. (2) The assessment or reassessment made under subsection (1) shall be at the rate at which it would have been made	 had there been no under assessment or escapement." The Bombay Sales Tax Laws	 (Validating Provisions and Amendment) Act	 1959 inserted the following sub section (3) in section 11A: "(3)(a) Nothing in sub sections (1) and (2) (i) shall apply to any proceeding (including any notice issued) under section 11	 or 22A or 22B	 and (ii) notwithstanding any judgment	 decree or order of a court or Tribunal	 shall be deemed ever to have been applicable to such proceeding or notice. (b) The validity of any such proceeding or notice shall not be called in question merely on the ground that such proceeding or notice was inconsistent with the provisions of subsections (1) and (2). " 681 The appellant is a registered dealer. It failed to file returns for the periods 1 5 1952 to 31 10 1952	 1 11 1952 to 31 10 1953	 1 11 1953 to 31 10 1954 and 1 11 1954 to 31 10 1955. The Sales Tax Officer	 Non resident Circle	 Nagpur issued four notices to the appellant initiating proceedings under sections 10(3)	 11(4)	 11A(1) and 22C(1) of the Act. The appellant filed a writ petition in the High Court challenging the notices and asking for an order restraining the respondents from taking steps under the notices and making assessments or levying penalties in respect of the aforesaid periods. The High Court dismissed the application. From this order	 the appellant has preferred the present appeals. Notices under section 22C(1) can be issued only in course of any proceedings under the Act. As no proceedings were pending against the appellant	 no notice under section 22C(1) could be issued to it. We shall presently show that no notice can be issued to a registered dealer under section 11A(1) for assessing the turnover which has escaped assessment by reason of his not filing a return. The impugned notices so far as they were issued under sections 22C(1) and 11A(1) may be treated as surplusage and rejected. Under section 10(3)	 if a registered dealer fails to furnish his return for any period within the prescribed time without any sufficient cause	 the Commissioner may after giving him reasonable opportunity of being heard direct him to pay by way of penalty a sum not exceeding one fourth of the amount which may be assessed on him under section 11. If no assessment can be made under section 11	 no penalty can be levied under section 10(3). Therefore	 the point for determination is whether the impugned notices so far as they were issued under section 11(4) are valid. The contention of the appellant is that the notices under section 11 (4) are invalid as they were not issued within three years from the expiry of the aforesaid periods. We see no force in this contention. Section 11(4) does not prescribe a period of limitation for the issue of a notice under it. In Ghanshyam Das vs Regional Assistant Commissioner of Sales Tax	 Nagpur(1)	 the Court by a majority decided with reference to section 11.(4) and section 11A	 as it stood before its amendment by the Bombay Sales Tax Laws (Validating Provisions and Amendment) Act	 1959	 that a notice under section 11(4) initiates new proceedings and it also decided or to be more accurate	 assumed that the period of limitation prescribed by section 11A(1) should be imported into section 11(4). The case was decided without reference to section 11A(3) inserted by the Amending Act and is no authority on the interpretation of that sub section. Section 11A(3) now expressly provides that nothing in section 11A(1) shall apply to any proceeding including any notice issued under section 11. The section is retrospective in operation. It follows that the period of (1) 	 682 limitation prescribed by section 11A(1) cannot be applied to a proceeding or a notice issued under section 11(4). There is no period of limitation prescribed for a notice or a proceeding initiated under section 11(4). Consequently	 the impugned notices issued under section 11 (4) are not barred by limitation and are not invalid. The argument then is that section 11(4)(a) offends article 14 of the Constitution in two ways. Firstly	 it is said that it is open to the sales tax authorities to proceed at their sweet will either under section 11(4)(a) or under section IIA(1) against a registered dealer for his failure to file returns and the principle of Shree Meenakshi Mills Ltd. vs Sri A. V. Viswanatha Sastri and Another(1) is invoked. We find no merit in this contention. Section 11(4)(a) specially pro vides for the initiation of proceedings against a registered dealer who has not furnished returns in respect of any period by the prescribed date. Having made this special provision	 the legislature must be taken to have intended that in a case falling under section 11(4)(a) the sales tax authorities must proceed against the registered dealer under section 11(4)(a) and not under section IIA(1). The special provision must be taken silently to exclude all cases failing within it from the purview of the more general provision. Moreover if a statute is capable of two constructions	 that construction should be given which will uphold it rather than the one which will invalidate it. Construing sections 11(4)(a) and 11A(1) together we should	 therefore	 hold that the cases falling within section 11(4)(a) are excluded from the purview of section 11 A(1). The point that there is no over lapping of sections 11(4)(a) and 11A(1) is made clearer by s.11A(3). The decisions under section 34(1)(b) of the Indian Income tax Act	 1922 such as Maharaj Kumar Kamai Singh vs Commissioner of Incometax	 Bihar and Orissa(2) and under section 14 of the Business Profits Tax Act	 1947 such as Commissioner of Income Tax vs Narsee Nagsee & Co.(2) are distinguishable. In those Acts	 there was no special provision corresponding to section 11(4) for proceeding against registered dealers who have not filed returns	 and the question how far the special provisions would exclude cases within it from the purview of the more general provision could not arise. In Ghanshyam Das 's case(3)	 none of the notices in question was issued under section 11A	 and the Court did not say that a registered dealer could be proceeded against under section 11 A for not filing a return. Nor did the Court consider the effect of section 11 A(3). It is true that the majority decision held that the phrase "escaped assessment" in section 11A includes that of a turnover which has not been assessed at all because no assessment proceedings were initiated. But having regard to the special provisions of section 11(4) read with section 11A(3)	 the power under section 11 A(1) as interpreted in Ghanshyam Das 's case(4) to assess turnover which escaped assessment by reason of non filing of returns must be confined to cases of (1) (2) [1959] Supp. 1 S.C.R. 10. (3) 	 (4) ; 683 unregistered dealers. As pointed out already	 cases of registered dealers falling within section 11(4) are excluded from the purview of section 11A(1). It is next said that section 11 (4) offends article 14 of the Constitution because no period of limitation is prescribed for a notice under it	 whereas periods of limitation are prescribed for notices under sections IIA(L) and 11(5). We see no merit in this contention. The Act 'deals with registered and unregistered dealers differently in many ways. The classification and differential treatment of re gistered and unregistered dealers are based on substantial differences having reasonable relation to the object of the Act. A registered dealer unlike an unregistered dealer is under a statutory obligation to file returns without any notice being served upon him and to pay the full amount of tax due from him before furnishing the return (sections 10 and 12). A dealer who has registered himself under the Act admits his liability to furnish returns whereas a dealer who has not registered himself makes no such admission. A registered dealer has certain advantages under the Act which are denied to an unregistered dealer. Section 2(1)(a)(ii) exempts from tax sales of a registered dealer of goods specified in his certificate of registration as being intended for use by him as raw materials in the manufacture of goods for sale by actual delivery in the State for consumption therein. An unregistered dealer cannot get the benefit of this exemption. Moreover	 section 2(j) (a)(ii) exempts from tax sales to a registered dealer of goods de clared by him in the prescribed form as being intended for resale by him by actual delivery in the State for consumption therein. The sales to an unregistered dealer are not so exempt. Consequently	 a registered dealer call buy his goods from the producer or the wholesaler at a cheaper price and has thus ail economic advantage over an unregistered dealer. In the matter of penalties	 sections 10(3) and 22C(1) treat the two classes of dealers on the same footing	 but sections 11 (4)	 11(5) and 11 A(1) treat them differently. No penalty can be levied on a registered dealer under section 11(4) but heavy penalties may be levied on an unregistered dealer under sections 11(5) and 11A(1). While prescribing periods of limitation for proceedings against an unregistered dealer under sections 11(5) and 11A(1)	 the legislature has wisely not prescribed a period of limitation for a proceeding initiated under section 11(4)(a) against a registered dealer considering that (1) the registered dealer is under a statutory obligation to file the return	 (2) no penalty is leviable under section 11(4)and (3) the registered dealer is given many advantages under the Act which are denied to an unregistered dealer. The bar of limitation in the case (if an unregistered dealer and the absence of such a bar in the case of a registered dealer cannot be regarded as unjust or discriminatory. Questions of policy are not to be debated in this Court. There is no compulsion on the legislature to prescribe a period of limitation in every case. In taxing statutes the legislature has a large measure of discretion. We cannot strike 684 down section 11(4)(a) because of some preconceived notion that the same period of limitation should be prescribed for proceedings against both registered and unregistered dealers. In Ghanshyam Das 's case(1)	 Raghubar Dayal	 J. at p. 459 clearly held that section 11(4) is not violative of article 14. The majority did not dissent from this opinion. We hold that section 11 (4) is not violative of article 14 and we uphold it. It follows that the notices issued on July 8	 1959 under section 11(4) are valid in respect of the entire period from 1 11 1952 to 31 10 1955. As regards the alternative contention of the respondent	 that the notices issued in 1955 validly initiated	 proceedings under section 11(4) for the period from 1 2 1953 to 31 10 1955 we are glad to find that the majority has accepted this contention. The irregularities	 if any	 in the notices do not invalidate them. However	 for the reasons already mentioned	 we are of opinion that the impugned notices issued on July 8	 1959 are valid. In the result	 the appeals are dismissed with costs. ORDER In accordance with the opinion of the majority these appeals are partly allowed with respect to turn over from 1 5 1952 to 31 1 1953. In other respects the appeals are dismissed. No order as to costs.

Under s.10(1) of the Central Provinces and Berar Sales Tax Act 1947 every dealer required so to do by the Commissioner by notice	 and every registered dealer	 shall furnish such returns by such dates and so such authority as may be prescribed	 and r.19 of the Rules framed under the Act provides that every registered dealer should furnish quarterly returns accompanied by a treasury challan in proof of payment of the tax payable. If the registered dealer does not so furnish his return	 the Commissioner may	 after giving the dealer a reasonable opportunity assess him to the best of his judgment (4)(a). Under s.11(4) (a). Rule 32 prescribes that ordinarily not less than 30 days notice should be given to an assessee for submitting his explanation before action is taken under s.11(4)(a). In 1953	 s.11A was added to the Act. Under s.11A(1) if in consequence of any information which has come into his possession	 the other Commissioner is satisfied that any turnover of a dealer has escaped assessment	 the Commissioner may	 within three calendar years from the expiry of such period	 after giving the dealer a reasonable opportunity of being heard	 proceed to re assess the tax payable on any such turnover and also direct the dealer to pay a penalty. In 1959	 s.11A(3) was added by which	 nothing in s.11A(1) shall apply to any proceeding including any notice under s.11	 that is	 the period of limitation of 3 years mentioned in s.11A(1) shall not apply to a proceeding under s.11(4)(a) on best judgment basis. The appellants were registered dealers. Their assessment year was from 1st November to 31st October. They submitted their quarterly returns upto 30th April 1952. Since no returns were submitted thereafter	 on 13th September 1955	 the assessing authority issued a notice with respect to the period 1st January 1953 to 31st December 1953 calling upon them to show cause why action should not be taken against them under s.11(4) (a). A similar notice was issued on 27th October 1955 for the period 1st January 1954 to 31st December 1954	 and on 7th July 1956	 for the period 1st January 1955 to 31st December 1955. The appellants repeatedly took time for submitting their explanation. In 1958	 fresh notices were issued for L/P(N) 7SCI (3)(a) 662 the calendar years1952 to 1955 and the appellants raised the objection	 for the first time	 that their assessment year was not the calendar year	 but 1st November to 31st October. In view of that objection	 the first respondent issued another set of notices on 8th July 1959 for the periods 1st May 1952 to 31st October 1952	 1st November 1952 to 31st October 1953	 1st November 1953 to 31st October 1954 and 1st November 1954 to 31st October 1955 respectively. The appellants contended that those notices were barred by the 3 year period of limitation under s.11A(1)	 but the assessing authority assessed the appellants on best judgment basis under section 11 (4) (a). The appellants thereupon filed writ petitions in the High Court challenging the validity of the notices and the order of assessment	 but the petitions were dismissed. In appeals to this Court	 the appellant contended that: (1) Section 11(4)	 (a) read with s.11A(3) contravenes article 14 of the Constitution	 because	 a registered dealer who had failed to submit his return could be proceeded against either under s.11(4)(a) or s.11A(1)	 but	 whereas s.11A(1) provides a 3 year period of limitation	 a proceeding under section 11(4)(a) could be initiated at any time in view of s.11A(3); (2) the notices of 1959 were barred by time; and (3) the notices of 1955 and 1956 were not valid	 because	 (a) the issue of one notice for several quarters was contrary to law	 (b) that portion of the printed notice which said that the appellants had failed to furnish the return as required by a notice in that behalf served on them under s.10(1) did not apply to the appellants as no notice under s.10(1) had been given to them	 (c) the assessment year mentioned in the notice was the calendar year which was not the assessment year of the appellants	 and (d) though r. 32 provides that ordinarily not less than 30 days notice should be given to the assessee for submitting his explanation	 the first notice gave to the appellants only 9 days time. Held: (Per Wanchoo C. J.	 Mitter and Hegde	 JJ.) (1) Section 11(4) (a) is void as it is violative of article 14. The expression 'dealer ' in s.11A(1) includes both registered and unregistered dealers	 and it cannot be contended that dealers are classified into registered and unregistered dealers	 the former coming under s.11(4)(a) and the latter under s.11A(1). To be a valid classification	 it must not only be founded on an intelligible differential which distinguishes persons and things that are grouped together from others left out of the group	 but that differentia must have a reasonable relation to the object sought to be achieved. In the present case	 both s.11(4)(a) and section 11A(1) are concerned with taxing escaped assessments	 and judged from this object sought to be achieved by the Act	 the classification of dealers into registered and unregistered dealers is not reasonable. Therefore	 even registered dealers are covered by section 11A(1). As the 'information ' contemplated by s.11A(1) need not be from outside sources but could be gathered by the assessing authority from his own records	 his knowledge of the facts that the appellants had not submitted quarterly returns and treasury challans and that they were notassessed to tax with respect to the turnovers in question constituted 'information ' to the assessing authority from which he could be satisfied that the turnovers had escaped assessment. It would thus be open to the assessing authority to proceed against the appellants either under s.11(4)(a) or s.11A(1). But as they were proceeded against under section 11(4)(a)	 they could not get the benefit of the limitation prescribed under section 11A(1). It follows that section 11(4)(a) has become a discriminatory provision in view of section 11A(3)	 [672 B; 674 D E; 675 H; 676 A G]. 663 Ghanshyam Das vs Regional Assistant Commissioner of Sales tax	 Nagpur ; and Suraj Mall Mohta & Co. vs A	 V. Visvanatha Sastri & Anr. ; 	 followed. Maharaj Kumar Kamal Singh vs Commissioner of Income tax	 Bihar & Orissa [1959] Supp. 1 S.C.R. 10	 Commissioner of Incometax	 Bombay City vs M/s. Narsee Nagsee & Co. Bombay	 Salem Provident Fund Society Ltd. vs C. I	 T. Madras	 and United Mercantile Co. Ltd. vs Commissioner of Income tax	 Kerala	 referred to. (2) But s.11(4)(a) is severable from the rest of the Act and its severance does not affect the implementation of the other provisions of the Act. Therefore	 the validity of the notices should be tested under s.11A(1). So tested	 the notices of 1959 are all barred by the 3 year period of limitation. [676 G H]. (3) Since there was no valid notice for the period 1st May 1952 to 31st October 1952	 there could be no assessment in respect of that period. As regards the quarter 1st November 1952 to 31st January 1953 also	 there was no valid notice. The notice issued on 13th September 1955	 no doubt refers to the period 1st January 1953 to 31st January 1953	 but that is only a part of the quarter. As a quarter is a unit in itself and there should be a notice for the entire quarter	 the proceeding in respect of the quarter from 1st November 1952 to 31st January 1953 is also barred by limitation [677 E F]. But the notices issued in 1955 and 1956 are valid notices in so far as they relate to the period 1st February 1953 to 31st October 1955. Any irregularity in the issue of the notices does not vitiate the proceeding	 because	 the liability to pay tax is founded on the charging sections. [680 B C]. Chatturam & Ors. vs C.I.T. Bihar	 ; 	 applied. Further	 (a) The issue of one notice for several quarters is not contrary to law. [678 E]. State of Orissa and Anr. vs M/s. Chakobhai Chelabhai & Co. ; 	 followed. (b) The assessing authority	 by mistake	 had failed to strike out the portion in the printed form which was inapplicable to the appellants who were registered dealers and on whom no notice need be served to furnish a return. But this circumstance could not have prejudiced the appellants and such a mistake does not vitiate the notice. [678 H]. Chakobhai Chelabhai 's case; 	 	 followed. (c) The mistake as regards the assessment year in the notices does not render the notices invalid. The assesses deliberately kept silent and when they felt that the period of limitation prescribed by section 11A had expired	 brought the fact to the notice of the authority. The assesses were not prejudiced and could not be permitted to take advantage of such a mistake. [679 G H]. (d) Rule 32 prescribes that ordinarily 30 days ' notice should be given. Therefore	 the period is not mandatory. All that ss.11(4) and 11A require is that an assessee should be given a reasonable opportunity before he is proceeded against. Since	 in the present 664 A case	 the appellants appeared before the assessing authority and did not object to the validity of the notices but asked for sub mitting their explanation	 and as the time asked for was given	 the appellants had a reasonable opportunity	 for submitting their explanation. [679 D G]. (Per Bachawat and Ramaswami JJ.) (1) Section 11(4) is not violative of article 14. Construing ss.11(4)(a) and 11A(1) together it must be held that cases falling within s.11(4)(a) are excluded from the purview of S.11A(1). Section 11(4)(a) specially provides for the initiation of proceedings against a registered dealer. Having made this special provision	 the legislature must be taken to have intended that the sales tax authorities must proceed against. a registered dealer under s.11(4)(a) and not under s.11A(1). [683 C B]. The classification and differential treatment of registered and unregistered dealers are based on substantial difference having a reasonable relation to the object of the Act. The legislature did not prescribe a period of limitation for a proceeding initiated under section 11(4)(a) against a registered dealer	 because	 (i) the registered dealer is under a statutory obligation to file a return	 (ii) no penalty is leviable under s.11(4) and (iii) the registered dealer is given many advantages under the Act which are denied to an unregistered dealer. Therefore	 the bar of limitation in the case of an unregistered dealer and the absence of such a bar in the case of a registered dealer cannot be regarded as unjust or discriminatory.[684 B	 G H]. Ghanshyam Das vs Regional Assistant Commissioner of sales Tax Nagpur	 [1964]4 S.C.R. 436	 Maharaj Kumar Kamal Sing vs Commissioner of Income tax	 Bihar & Orissa	 [1959] Supp. 1 S.C.R. 10 and Commissioner of Income tax vs Narsee Nagsee & Co. 	 explained. (2) Section 11A(3) expressly provides that nothing in section 11 A(1) shall apply to any proceeding including any notice under section 11 and the section is retrospective. It follows that the period of limitation provided by s.11A(1) cannot be applied to a proceeding or notice under section 11(4). Consequently	 the impugned notices of 1959	 issued under s.11(4) are not barred by limitation and are not invalid [682 H; 683 A]. Ghanshyam Das 's Case; 	 	 referred to (3) Even the notices issued in 1955 and 1956 initiated proceedings validly under section 11(4) for the period from 1st February 1953 to 31st October 1955	 as the irregularities in the notices did not invalidate them. [685 B C].