Das, J. — We propose to dispose of these bunches of Civil Rules by a common judgment as they involve similar facts and identical questions of law under Assam Finance (Sales Tax) Act, 1956 and Assam Finance (Sales Tax) Rules, 1956. 2. The Assam Finance (Sales Tax) Act, 1956 was brought into force with effect from 1.7.56. The validity of this Act was challenged before this Court in Satyanarayan Mahavir vs. State of Assam (AIR 1971 Assam & Nagaland 83). It was held that the Act doss not offend the provisions of Article 301, 19(l)(g) and 14 of the Constitution of India. The main object of the Act is to impose a tax on dealers for sales of commodities in Assam as prescribed in the Schedule annexed to the Act. By virtue of section 39 of the Act which empowers the State Government to ma e Rules, the Assam Finance (Sales Tax) Rules 1956 was framed which was given effect on and from 27.6.56 and as amended from time to time. 3. The Assam Finance (Sales Tax) Act, 1956 (for short, 'the Act') was amended from time to time and one of such amendments was made in 1977 which came into force with effect from 15.12.77. This would be relevant for our consideration with respect to few of the cases we are to deal with. Similarly, Assam Finance (Sales Tax) Rules, as amended in 1968 was published in Assam Gazette (Part HA) dated 25.6.69. This amendment was given effect retrospectively from 1.1.68. This would also be relevant for the purpose of these cases. It is needless to say that a legislation or a statute is enacted to achieve some public purpose and the policy of law and the object sought to be achieved can furnish reliable guidelines for required exercise of discretionary power. It is also very clear that if a statute declares a definite policy, it must have a definite standard for the rule against the delegation of legislative power and also for equality if the standard is reasonable. The Act thus proposes to impose a liability on traders to pay tax on sales of taxable commodities as prescribed in the schedule to the Act. 4. The Act thus proposes to impose a liability on traders to pay tax on sales of taxable commodities as prescribed in the schedule to the Act. 4. These bunches of Civil Rules have arisen out of demand notices issued by the Superintendent of Taxes directing the petitioners to pay interest for non-payment of full quarterly tax payable under Assam Finance (Sales Tax) Act, 1956 (for short, the Act). The period mentioned are different as per demand notices. The petitioners are registered dealers of the commodities within the meaning of sub-section (2) of section 2 of the Act in respect of which Sales Tax are payable under the Act. 5. Some of the Civil Rules relate to the demand for payment of interest for the period prior to coming into force of the Assam Finance (Sales Tax) Amendment Rules, 1968 (for short, the Amended Rules). The petitioners have also challenged the validity of notices demanding interest as being violative of the provisions of section 12(1) of the Act and the Rules 32A and 32B of the Rules to be ultra vires, invalid and beyond legislative competence of the State Legislature to frame such Rules. Therefore, all these cases are covered by two sets of arguments, one relating to validity of retrospective operation of the Amended Rules, 1968 and the levy of interest after two years of" the completion of the assessment and the other relating to the validity of tie provisions of section 12(1) of the Act and Rules 32A and 32B of the Rules. 6. All the assessees who are the petitioners in these Civil Rules are registered dealers under the ] Assam Finance (Sales Tax) Act. The provisions of the Act requires every dealer to pay tax under the Act and to furnish in the prescribed form a return of his quarterly turnover for a year. The assessees filed their quarterly returns but did not pay the tax due according to such returns. The tax due was paid by the assessees but not within the period it ought to have been paid. In few cases the full amount of tax was not paid and in such cases the assessing authority levied interest but after making the assessment. The tax due was paid by the assessees but not within the period it ought to have been paid. In few cases the full amount of tax was not paid and in such cases the assessing authority levied interest but after making the assessment. However, the petitioners of the cases before us fall into the following categories, namely, (1) dealers who had filed their returns but, had not deposited the tax due from them and the assessing authority had determined the amount of tax payable by them and issued notice calling upon them to deposit the amount of tax ; (2) dealers who had to deposit the full amount according to their returns and the assessing authority issued demand notice on them to pay the amount of tax but not interest ; (3) dealers who had filed their returns and paid tax due according to the returns after expiry of prescribed time and in whose cases the assessing authority had accepted the returns and had issued demand notice on them to pay tax and thereafter assessed interest after 2 years on the amount of tax for the period for which such payment was delayed. 7. One of the root points as advanced in all these cases relates to levy of interest after completion of assessment and issue of demand notices for payment of such interest. The second significant question which arises in these cases is as to whether after completion of final assessment the authority could levy interest and issue demand notices for payment of interest without taking recourse to rectification proceedings as provided under section 12 of the Act. In the context of the above the next question would come for consideration as to whether the interest could at all be levied when the final assessment was made for payment of required tax. Admittedly, in several cases no rectification proceeding was recorded to for enhancing the earlier assessment by levying interest. The assessments for payment of taxes in these cases were completed in 1973 and the required tax was also paid by the respective dealers after such assessment. The notice of demand for levy of interest was issued in the year 1975 after about 2 years from the date of final assessment. The assessments for payment of taxes in these cases were completed in 1973 and the required tax was also paid by the respective dealers after such assessment. The notice of demand for levy of interest was issued in the year 1975 after about 2 years from the date of final assessment. The petitioners have challenged such levy of interest for different periods after assessment was completed and that too without giving any opportunity to the petitioners of being heard. 8. Before taking up the various aspects of the argument as advanced by the respective counsel of the parties, it would be appropriate to refer certain relevant provisions of the Act. Section 3 of Act provides that every dealer in taxable goods shall pay a tax on his turnover at the rates specified in column 3 of the Schedule attached to the Act subject to such rebate which may be granted by the State Government on fulfilment of certain conditions. The d3aler has been defined in clause (2) to mean any person who carries on the business of selling taxable goods in Assam. Section 8 of the Act provides submission of return by every registered dealer of his turnover within prescribed date. Section 9 of the Act empowers the Commissioner to assess the dealer and to determine the tax payable by him on the basis of his return if the return appears to be correct and complete. It prescribes the provisions relating to non-submission of return and in a case where the Commissioner is not satisfied as to the correctness of the return. The charging section of the Act speaks about the dealer and the provisions of section 8 make it obligatory for every registered dealer to furnish return of his turnover. Section 12 of tb.3 Act provides for rectification of orders of assessment which is quoted herein below :- "12. The charging section of the Act speaks about the dealer and the provisions of section 8 make it obligatory for every registered dealer to furnish return of his turnover. Section 12 of tb.3 Act provides for rectification of orders of assessment which is quoted herein below :- "12. Rectification of orders.-(1) The authority which made an assessment or passed an order on appeal or revision in respect thereof, may, at any time within three years from the date of such assessment or order and of its own motion, rectify any mistake apparent from the records of the case, and shall, within the like period, rectify any such mistake as has been brought to its notice by a dealer; Provided that no such rectification shall be made having the effect of enhancing the assessment unless the authority concerned has given notice of its intention so to do and has allowed him a reasonable opportunity of being heard. (2) Where any such rectification has the effect of reducing the assessment, a refund shall be due to the dealer. (3) Where any such rectification has the effect of enhancing the assessment, a notice of demand shall be issued for the sum payable." One of the main thrust of argument centres round the application of aforesaid provision of section 12(1), relating to the levy of interest without taking recourse to the rectification proceedings of the earlier assessment order. 9. Now, let us have a cursory glance to the provisions of Rule 32A and 32B which have also been challenged as ultra vires and beyond the legislative competence of the State Legislature. Rules 32A and 32B are both amended provisions of the former Rules which were published in the Assam Gazette, Part II A dated 25. 6. 69 and brought into force with effect from 1.1.68. The provisions of Rule 32A prescribes the rate of simple interest that could be levied for failure of submitting the return and payment of required tax due by a dealer within the period prescribed under Rule 17 of the Rules and of the proviso therender. Rule 32A of the Rules runs as follows :- "32A. The provisions of Rule 32A prescribes the rate of simple interest that could be levied for failure of submitting the return and payment of required tax due by a dealer within the period prescribed under Rule 17 of the Rules and of the proviso therender. Rule 32A of the Rules runs as follows :- "32A. If a dealer does not submit the return and pay the amount of tax due from within the period specified in Rule 17(1) and the proviso thereunder, he shall be liable to pay a simple interest at the following rates :- (a) for the first quarter '... Nil (b) after the first quarter and for the second quarter ... 6 % per annum. (c) after the second quarter and for the third quarter ... 6 % per annum. (d) after the third quarter and for the fourth quarter ... 12 % per annum. (e) after the fourth quarter ... 24 % per annum. Provided that where a dealer has paid a part of the tax due on any date after the expiry of thirty days of the end of each quarter, he shall be liable to pay interest at the appropriate rates on the whole of the amount of tax assessed upto the date of part payment and thereafter on the balance tax payable." Rule 32B is also quoted as under:- "32B. The amount of tax due at the close of each quarter or period and the interest shall be levied in like manner as provided for in Rule 32A and the proviso thereunder." 10. On hare reading of both the provisions of Rule 32A and 32B of the Rules it appears that Rule 32A prescribes levy of simple interest in case the dealer fails to submit the return and pay the amount of due tax within the period specified in the Rules. Therefore, under the provisions of Rule 32A above, a dealer is liable to pay due tax on the basis of his submission of return as per his estimate of quarterly turnover. Rule 32B speaks about non-payment of tax due at the close of each quarter or period assessed on the dealer either in the case of his non-submission of return or otherwise and in such case the interest shall be levied on such amount in the like manner as prescribed in Rule 32A and the proviso thereunder. 11. We have heard Mr. 11. We have heard Mr. J.P. Shattacharjee and Dr. B. P. Saraf, Isarned counsel for the petitioners and Mr. N. M. Lahiri, learned Advocate General Meghalaya appearing on behalf of the respondent the State of Assam in all the cases. 12. If we go back to the legislative history it appears that the provisions of section 22A of the Act was incorporated for the first time by Amendment Act of 1967. Prior to 1967 there was no like provision in the Act. Section 22A after it was incorporated in 1967 reads as follows :- "22A. Interest payable by dealer- (1) If any registered dealer does not pay into a Government Treasury the full amount of tax due from him under the Act on the basis of the return or his account books within the prescribed date, simple, interest at the rate of six per cent per annum from the first day of the month next following the said date shall be payable by the dealer upon the amount by which the tax so paid falls short of the amount of tax payable as per his return or account books. If such amount of tax and interest are not paid within thirty days from the date from which the interest is due, simple interest upto a maximum of 24 per cent per annum shall be payable as may be prescribed. (2) Where on making the assessment, the Commissioner finds that a dealer has not maintained the account books properly and thereby he has suppressed the sale of goods in any period, the Commissioner may direct him to pay interest as prescribed in sub-section (1). If the amount of tax payable under the Act has been reduced in appeal or revision, the interest may be calculated on the reduced amount. If the amount of tax payable under the Act has been reduced in appeal or revision, the interest may be calculated on the reduced amount. (3) If any registered dealer does not pay into the Govern­ment Treasury the amount of tax within the date as provided in sub-section (4) of section 22 or any instalment of tax within the extended date as per proviso to sub-section (1) of section 23 of tile Act, interest as provided in sub-section (1) shall be payable from the first day of the month next following the said date by the dealer upon the amount by which the tax if any paid falls short of the amount of tax payable under the Act." By amendment Act of 1969 a new sub-section namely sub-section (4) of section 22A was incorporated which came into effect on and from 1.4.69. 13. As regards incorporation of the new provisions of the Act and the provisions of Rules, namely, 32A and 32B of the Rules, it is submitted by Dr. Saraf that the Rule making authority have not been vested with any such power to make rule giving a retrospective' effect of it. The amended rules with insertion of 32A and 32B were published on 25.6.69. and were given retrospective effect from 1.1.68. In support of his aforesaid contention about the competency of the Rule making authority to give such retrospective effect to any Rule a reference is made on a decision rendered by this Court in M/S Shree Hanuman Match Works & Anr. Etc. vs. The State of Assam & Ors. : (1982) 1 GLR 181. This was a case under the Assam Finance (Sales Tax) Act, 1956 and Assam Finance (Sales Tax) Rules, 1956. One of the questions that arose in the said case was as to whether there could be any retrospective effect of the Assam Finance (Sales Tax) (Amendment) Rules 1968. In paragraph 6 it was held by this Court- "6. The last three grounds of challenge may be taken up first. So far as the retrospectiveness of the new Rule 46A is concerned, it is clearly stated by the learned Advocate General, Meghalaya, who has appeared on behalf of the res­pondents, that this could not have been done as the Act has not conferred the power to make rules with retrospective effect. So far as the retrospectiveness of the new Rule 46A is concerned, it is clearly stated by the learned Advocate General, Meghalaya, who has appeared on behalf of the res­pondents, that this could not have been done as the Act has not conferred the power to make rules with retrospective effect. When a statute does not so authorise a rule making authority, cannot give retrospective effect to the rules." This appears to be the settled position of law. 14. In course of submission Dr. Saraf, learned counsel for the petitioners has also drawn our attention to prescribed form of assessment order, namely Form V-B which provides levy and demand of interest under section 22 (1) to form a part of the assessment order. To cover up the arguments of all the Civil Rules the learned counsel for the petitioners have urged before us the following points :- That the provision of section 22A of the Act is violative of section 15 of the Central Sales Tax Act, 1956 with Article 286 of the Constitution of India and it is beyond the legislative competence of the State legislature to enact the provisions being not covered by item 54 of list 2 of the 7th Schedule of the Constitution to levy such interest to the maximum of 24% per annum in case the amount of tax and interest are not paid within 30 days from the date from which the interest is due. In the aforesaid context it is further submitted by the learned counsel for the petitioners that it suffers from vice of excessive delegation inasmuch as essential legislative function in the matter of fixation of rate of interest has been delegated to the executive without any control of guidelines in this matter. The next ground of attack is as to the validity of Rule 32A and 32B of the Assam Finance (Sales Tax) Rules 1956 as amended. It is submitted by the learned counsel that these two rules as incorporated, namely, 32A and 32B of the amended Rules read with section 22A of the Act are beyond competence of Rule making power of the State legislature. Section 22A of the Act provides the levy of interest 24% per annum as a maximum amount of interest for failure of the dealer to pay due tax and the interest within 30 days from the date from which the interest falls due. Section 22A of the Act provides the levy of interest 24% per annum as a maximum amount of interest for failure of the dealer to pay due tax and the interest within 30 days from the date from which the interest falls due. But the provision of Rule 32A provides for levy of interest in case of non-submission of return and also for non-payment of amount of tax due by a dealer. It provides for imposition of interest at different rates varying from 6% to 24% on default of payment of tax for 2nd, 3rd and 4th quarters and maximum interest could be assessed at the rate of 24% per annum after default of 4th quarter. However, for the first quarter the interest is not levied. According to learned counsel for the petitioners this Rule 32A is not in accordance with the provision of section 22A of the Act and as such, the Rules may be treated as incongruous and inconsistent and contrary to the provisions as laid down under section 22A of the Act. The next submission of the learned counsel is as regards retrospective effect of the Rules. According to the learned counsel There is no express or implied power to give the Rule a retrospective effect and in case it operates retrospectively, it must be held to be invalid. 15. With regard to the factual aspect of the case the learned counsel for the petitioners have submitted that no interest can be levied atleast for the period in respect of which the proceedings under this Act were stayed by this Court and secondly as no interest was levied and demanded at the time of final assessment, the levy of interest afterwards amounts to enhancement of earlier assessment which cannot be done without affording an opportunity to the dealers of being heard in view of the requirement of the proviso to section 12(1) of the Act. 16. As regards the order pissed by the authority in levying interest it is submitted by toe learned counsel that this being arbitrary and non-speaking order it is liable to be quashed. In the above context and in support thereof several decisions were placed before us by the learned counsel of both the parties which we would refer in seriatim. Before taking up those decisions for consideration it would be apposite to record the arguments advanced by Mr. In the above context and in support thereof several decisions were placed before us by the learned counsel of both the parties which we would refer in seriatim. Before taking up those decisions for consideration it would be apposite to record the arguments advanced by Mr. Lahiri, learned Advocate General representing the State of Assam, the respondent in these cases. The following submissions were made by Mr. Lahiri, learned counsel for the respondent :- (a) That in the present nature of the cases the question of applicability of section 12 of the Act does not arise. According to the learned counsel no rectification proceeding is required to be taken up for levy of interest and the assessing authority is competent to issue the order and demand notice for payment of interest to the dealers who have defaulted to pay due tax for the period for which it becomes due. It is obligatory, as submitted by Mr. Lahiri, on every dealer to submit correct return and also to pay due tax and in failure of which, irrespe­ctive of the assessment made for the amount of tax due, the assessing authority can levy interest in a separate proceeding which does not require any rectification of the earlier order of assessment. Therefore, according to the learned counsel if a rectification proceeding is not taken up which in fact was not needed in the present nature of the cases, there was no obligation on the part of the authority to issue any prior notice to the dealer to afford an opportunity of being heard. (b) As regards the enhancement of the amount of total tax as assessed earlier it is submitted by Mr. Lahiri that the amount of interest which was levied subsequently was included in the demand notice under the provisions of the Act and the Rules made thereunder. Therefore, it is obligatory on the part of the dealer to pay interest at the rate prescribed under the relevant provisions of the Act and the" Rules made thereunder. Lahiri that the amount of interest which was levied subsequently was included in the demand notice under the provisions of the Act and the Rules made thereunder. Therefore, it is obligatory on the part of the dealer to pay interest at the rate prescribed under the relevant provisions of the Act and the" Rules made thereunder. While it is made obligatory on the part of the dealer to pay interest in case of default either for submission of return or in payment of due tax within the prescribed period, no duty is cast on the assessing authority to give the dealer a further hearing in case of levy of such interest as because the levy of interest in the present nature of the case was not as a result of the rectification proceedings as provided under section 12 of the Act but it was demanded, as submitted by the learned counsel for the respondent, as per mandatory provisions of the Act and the relevant Rules in respect of which a dealer is obliged to piy such interest in case of default as aforesaid. (c) As to the validity of the Rules and its retrospective operation, Mr. Lahiri has submitted that the State Government is empowered by virtue of section 39 of the Act to make its own Rule and that to for the purpose of giving effect to the provisions of the Act. Referring to entry 54 of the 7th Schedule to the Constitution, the learned counsel submits that it was neither an excessive delegation nor it prohibits the Stats authority to frame its own Rule to assess the quantum of interest to the maximum limit of 24% in conformity with the provisions of the Act. (d) As regards the exemption of payment of interest for the 1st quarter it is submitted by Mr. Lahiri that such concession can be allowed by the State Government while it has been authorised to make its own Rule by virtue of the provisions of section 39 of the Act. The State Government is also empowered to give a retrospective operation of the particular provisions of the Rules and to give retro­spective operation of a particular Rule does not necessarily make the Rule invalid. The State Government is also empowered to give a retrospective operation of the particular provisions of the Rules and to give retro­spective operation of a particular Rule does not necessarily make the Rule invalid. According to the learned counsel, it is neither unconstitutional nor violative of any of the provisions of the principal Act if it does not offend the provisions of the main Act. 17. Now before we consider the rival contentions of the parties let us consider the principle behind the Taxation Statute and the Rules under the statute. If the statute provides that taxation maybe made only by rules framed under the Act, no imposition can be made except in accor­dance with such rules and not by any executive order. A statute may authorise the executive to very the list of taxable commodities by addition or deletion, and even to fix rates of taxation. It is clear that the doctrine imposes on the rule making authority the duty of framing the rules only in "conformity to the provisions of the Act under which the rules are framed. If the rules are not warranted by the statute, the rules must be declared ultra vires. Article 265 of the Constitution lays down that no tax shall be lavied or collected except by authority of law, and law has been interpreted to mean rules, bye-laws or regulations provided the statute und«r which these rules etc. are made authorises the imposition. Though rules can be declared ultra vires the power of the authority to make such rules, what would be the position if the rules are declared to be part of the statute by using the formula "as if enacted in the Act" within the body of the statute ? The English case of House of Lords (Institute of Patent Agents vs. Lock wood) 1894 AC 347 interpreted these words to exclude the doctrine of ultra vires and to give the rules a freedom from judicial review. But in the subsequent case; (Minister of Health vs. The King) 1931 AC 464 Lord Dunodin held the words "as if enacted in the Act" do not bar judicial review. The same opinion was expressed by the Supreme Court in the case of State of Kerala vs. Abdulla & Co. But in the subsequent case; (Minister of Health vs. The King) 1931 AC 464 Lord Dunodin held the words "as if enacted in the Act" do not bar judicial review. The same opinion was expressed by the Supreme Court in the case of State of Kerala vs. Abdulla & Co. AIR 1965 SC 1585 to the following effect:- "Validity of a rule whether it is declared to have effect as if enacted in the Act or otherwise is always open to challenge on the ground that it is unauthorised." 18. To have a scrutiny of the rival contentions of both the parties, let us now discuss the merits and demerits of the cases of the parties with reference to the decisions which were placed before us for consideration and stated to be applicable in the present cases at hand. At the start we may refer to a case of M. Chockalingam and M. Meyyappan vs. Commissioner of Income Tax, Madras and another as reported in (1963) 48 IT R S C 34. That was a case where the Supreme Court dealt with the provision of section ISA (8) of Income Tax Act, 1922 and the proviso to section 35 (1) and Rule 48 of the Rules. The appellants Chock lingam and his brother did not pay Advance Tax according to their own estimate of the income for two years and consequently they were liable to pay penal interest under section 18A (8) of the Income Tax Act. However, the Income Tax Officer overlooked the fact and did not add penal interest to the tax leviable. The assessment was for the period 1951-52 and 1952-53. In 1956 the Income Tax Officer started proceeding under section 35 of the Income Tax Act for rectification of the assessment. No notice was issued to either brother, but the Income Tax Officer ordered the levy of penal interest. An application was made by both the brothers to Commissioner of Income Tax for revision of those orders. The revision application was rejected. Before the High Court both the brothers contended that there was a patent failure on the part of the Income Tax Officer to add penal interest to the tax and that subsequent1 assessment and levy of penal interest were opposed to the principle of natural justice as no opportunity of being heard was given to the petitioners. Before the High Court both the brothers contended that there was a patent failure on the part of the Income Tax Officer to add penal interest to the tax and that subsequent1 assessment and levy of penal interest were opposed to the principle of natural justice as no opportunity of being heard was given to the petitioners. However, the High Court dismissed the petition because in its opinion there was no substantial but a procedural defect and failure to issue notice would not have any effect even if notice had been issued. Their Lordshipi of the Supreme Court, however, held that High Court was wrong in holding that there was no breach of principle of natural justice and further held that the High Court ought to have quashed the order. It was observed and held :- "It will appear from this that the action under section 35 may be taken in favour of the tax payer without any notice to him but if the action has the effect of enhancing an assessment or reducing the refund, the Income-tax Officer, acting under section 35, must send a notice to the assessee and give him a reasonable opportunity of being heard." This admittedly was not done in these cases. It was incumbent upon the Income Tax Officer to give notice and a hearing to an assessee when the effect of rectification would be the enhancement of the assessment. This view of the Supreme Court was expressed in the context of the similar view as expressed in case of Sinha Govindji vs. Deputy Chief Controller of Imports & Exports reported in (1962) 1 S. C. R. 540. The aforesaid decision has been referred to us in the context of rectification of the order and it is submitted by the learned counsel for the petitioners that in case the total amount of assessment exceeds with addition of levy of interest, a hearing was needed. This is what the provision of sub-section (3) of section 12 of the Act provides. According to learned counsel that sub­sequent levy of interest was nothing but a rectification of the earlier order of assessment and, as such, for non-compliance of the provisions of section 12 of the Act, the impugned orders are liable to be quashed. The learned counsel for the petitioners have referred to us the 'Form VII' which has been prescribed in the Rules. The learned counsel for the petitioners have referred to us the 'Form VII' which has been prescribed in the Rules. In column 7 of Form VII which is used for final assessment of tax, the interest payable under section 22A read with Rules 32A and 32B upto the date of return/demand is included for the purpose of levy of interest. In column 3 of notice of demand in Form VII there is a reference to the liability to pay further interest by the assesses in accordance with the provision of section 22 A (1) read with Rules 32A and 32B of the Rules. It is submitted by the learned counsel that the assessing authority having failed to calculate the interest at the time of assessment and in the demand notice, the subsequent levy of interest must have been made on rectification of earlier assessment order. 19. Mr. Lahiri, learned counsel for the State has referred to us the case of M/S Royal Boot House Etc. vs. State of J & K and others as reported in AIR 1985 SC 1758 . It was a case under J&K General Sales Tax Act (20 of 1962). Section 8(3) of the said Act prescribes for payment of interest on default in payment of quarterly return and the interest becomes payable irrespective of issue of notice of demand. While upholding the decision of High Court, their Lordship of the Supreme Court ruled that there is no such requirement of issue of notice of demand in case of tax due on the basis of quarterly return to be filed by the dealer. Their Lordships held thus- "-..Where the tax due on the basis of quarterly return is not paid before the expiry of the last date of filing such return under the Act, it is not necessary to issue any notice of demand but on the default of being committed the dealer becomes liable under sub section (2) on the amount of such tax from the last date of filing quarterly return prescribed under the Act. In the present case it is the admitted position that tax due on the basis of quarterly return was not paid as required by sub-section (3) and the petitioner was, therefore, liable to pay interest on the amount of tax in respect of which default was committed at the rate prescribed in sub-section (2) from the last date prescribed for filing quarterly return under the Act upto the date of payment...•••” 20. In Kishan Lal Agarwalla & Anr. vs. The Agricultural Income Tax Officer, Assam . 1974 ALR 292 this Court had the occasion to deal with the provision of section 19 of Assam Agricultural Income-Tax Act, 1939 which subsequently was amended in 1967. In the said case the proceeding for assessment was initiated by issue of notice under section 19 (2) of unamended Act. In that case it was held that when the proceeding was started under unamended provision of section 19 of the Act, the assessment proceeding must be finalised keeping in view the unamended Act. It was further held that in view of section 6 of the Assam General Clauses Act it was quite clear that the assessment proceed­ing that was started by issuing notice under section 19 (2) of the unamended Act would have to be finalised in accordance with law. Referring to the case of Mahalakshmi Sugar Mills co. vs. Commissioner Of Income-Tax Delhi : 123 ITR page 429 it submitted by the learned counsel for the petitioners that liability to pay interest is as certain as the liability to pay tax. As soon as the prescribed period is crossed in the case of nonpayment of due tax the interest begins to accrue. Therefore, according to the learned counsel if the interest is a part and parcel of tax and in case of declared goods the interest cannot exceed 4% in any case of default. Therefore, the interest fixed by the State Legislature to the limit of 24% for delayed payment is excessive delegation of powers. 21. It appears that section 22A of the Act, 1956 was inserted by amendment Act of 1977 with effect from 15. 12. 77. Sub-section (3) of section 22A of the Act provides for interest which it liable to be paid by the dealer. 21. It appears that section 22A of the Act, 1956 was inserted by amendment Act of 1977 with effect from 15. 12. 77. Sub-section (3) of section 22A of the Act provides for interest which it liable to be paid by the dealer. If the dealer does not pay the full amount of tax payable by him under the Act in respect of any period from 1st day of January, 1968 and 30th September, 1977 before the commencement of the amended Act, 1977 it prescribes that in case of such default in payment of full amount of tax the dealer shall be liable to pay simple interest @ 24% per annum from the said date of commencement on the amount by which the tax is paid if any, before such commencement falls short of the tax payable. Therefore, the provisions of the Act prescribes a maximum limit of 24% interest in those cases that fall under sub-section (3) of section 22A of the Act. It is also provided in proviso to sub-section (4) of section 22A that where a dealer pays a part of the tax payable after due date or, in a case covered by sub-section (3) he shall be liable to pay interest at the appropriate rate on the whole of the tax payable upto the date of put payment and thereafter on the balance tax payable by him. Therefore, it cannot be said that fixation of rate and quantifying the rate of interest as per provisions of Rule 32A of Assam Finance (Sales Tax) Rules, 1956 (in short, the Rules) can be said to be an excessive delegation of powers and not in consonance with the provisions of the Act. But making the provisions of the Rule for giving any retrospective operation in demanding such tax prior to 25. 6. 69 (when the Rules were published in Assam Gazette) cannot be given effect to for the reason that .the fixation of rate of interest cannot have any retrospective effect. Reference can be made to a decision of this Court rendered in Hanuman Match Works (supra). All such questions were raised in the said case. It was a case under Assam Finance (Sales Tax) Act and the Rules. In that case Rule 46A which was inserted by an amendment in 1971 was given retrospective effect on and from 1. 1. 68. All such questions were raised in the said case. It was a case under Assam Finance (Sales Tax) Act and the Rules. In that case Rule 46A which was inserted by an amendment in 1971 was given retrospective effect on and from 1. 1. 68. It was held in that case that the statute does not authorise a rule making authority to give a Rule retrospective effect. 22. Here in this case the provisions of Rules 32A and 32B of the Rules were published on 25.6,69 by giving a retrospective effect from 1.1.68. For this though the Rules would not become invalid, but the retrospective operation would alone be ineffective. Therefore the new Rules must be deemed to have started operating on and from 26.6.69 and not retrospectively from 1.1-68. Therefore, the cases for the period ending 25.6.69 would not be covered by new provisions of Ruls 32A and 32B. It may further be said that the introduction of amended Rules 32A and 32B both have given relief to the dealer who fails to pay further tax payable for the period ending and in case of default The provisions have been made to give relief to a dealer from interest for the first quarter and for subsequent quarters interest at different rates shall be payable as prescribed under Rule 32A of the Rules. Therefore, in that context also it cannot be said that the provisions of the Rules are much more stringent and oppressive, Therefore, the aforesaid two Rules cannot be said to be ultra vires and violative of Article 14 of the Constitution of India. 23. Mr. N.M- Lahiri, learned counsel for the respondent hat submitted with reference to the case of M/S Haji Lal Mohd. Biri Works, Allahabad vs. The State of U.P. and others In 1973 SC 2226 that the liability to pay interest is automatic and arises by operation of law in case the default is committed. The amount of interest cannot be predicted till such time the payment of tax is made. But on the other hand it was known to the dealer that what would be the amount of interest in case they do not pay the full tax for the period. According to Mr. The amount of interest cannot be predicted till such time the payment of tax is made. But on the other hand it was known to the dealer that what would be the amount of interest in case they do not pay the full tax for the period. According to Mr. Lahiri it is a matter of mere arithmetical calculation to arrive at the figure of interest in these cases of default and as such there was no necessity of making another assessment or to take up any rectification proceeding by the assessing authority for levy of interest making it obligatory for him to issue a demand notice in respect of the interest to the dealer 24. In Central Provinces Manganese Ore Co. Ltd. C. I. T. as reported in AIR 1987 SC 438 their Lordships of the Supreme. Court while dealing with the provisions of Income Tax Act and the Rules relating to levy of interest under sections 139 and 215 of the Act observed and held- "...... Income-tax Act makes a clear distinction between the levy of a penalty and other levies under that statute. Interest is levied under sub-section (B) of S. 139 and under S. 215 because by reason of the omission or default mentioned in the relevant provision the Revenue is deprived of the benefit of the tax for the period during which it has remained unpaid. The very period for which interest is levied under the relevant provision points to the nature of the levy. If that is borne in mind, it will be apparent that the levy of interest is part of the process of assessment. Although S. 143 and S. 144 do not specifically provide for the levy of interest and the levy is in fact attributable to sub-section (8) of S. 139 or S. 215, it is nevertheless a part of the process of assessing the tax liability of the assessee....” 25. In the present cases at hand, there is no dispute that in case of default as prescribed under the aforesaid relevant provisions of law for submission of return or for non-payment of full tax due, the interest begins to accrue on unpaid amount of tax. In the present cases at hand, there is no dispute that in case of default as prescribed under the aforesaid relevant provisions of law for submission of return or for non-payment of full tax due, the interest begins to accrue on unpaid amount of tax. But while the assessment was completed in the year 1973 even for the period ending for a particular quarter, it was known to the assessing authority that the dealer was liable to pay interest for such default of payment of due tax. But the assessing authority failed to assess interest along with due assessment of tax though in the assessment form a separate column for assessment of interest under section 22A of the Act has been prescribed. The demand notice was issued after completion of assessment of due tax, but no interest was claimed. After about 2 years of completion of assessment, the impugned notices were issued to the dealers for payment of interest for default in due payment of lax thereby assessing the rate of interest as made payable by the dealer. However, it is not penal interest in that sense but it is an accrual of interest under the statutes as soon as default is committed. Therefore, the assessing authority under the statute had every right and jurisdic­tion to levy such interest in case of default of the dealer to pay due tax for the period ending for such assessment. Therefore, in that view of the matter the amount of interest is also to be treated as part of tax as because as per provisions of the statute, it is to be realised at the time of making assessment. Therefore, it appears to be an omission or mistake to demand tax with interest in the assessment order while it was completed in 1972 by which the amount of interest became due for the default id payment of due tax by the dealer. Therefore, it must be a mistake apparent on the face of the records not to calculate the interest at the time of completing the assessment by the assessing authority in respect of each quarter. That apart the actual tax payable by the dealer and the interest that accrued for such non-payment of tax makes an order on a total assessment of tax which is recoverable from the dealer for a particular period or quarter as the case may be. That apart the actual tax payable by the dealer and the interest that accrued for such non-payment of tax makes an order on a total assessment of tax which is recoverable from the dealer for a particular period or quarter as the case may be. The levy of interest as it accrues in case of default in payment of tax is also a part of tax because it is a statutory obligation on the part of the dealer to pay interest in case of default. Therefore, omission to assess the interest while it had accrued at the time of passing the order of assessment by the assessing authority it can only be done by way of taking recourse to rectification proceeding under section 12 of the Act and to make the dealer liable for payment of total amount of due tax and its interest in case of default. The subsequent assessment of interest by a follow up demand notice after 2 years amounts to reopening of the earlier assessment with the effect of enhancing the total amount of tax. If that be the position, the provision of sub-section (3) of section 12 of the Act is attracted. Therefore, the provisions as per proviso to section 12 must be followed, and a reasonable opportunity to the dealer of being heard must be afforded before such rectification is made for enhancing the amount of assessment. But in some cases it was not done. When the provisions of section 12 of the Act was not followed the demand notice issued to the affected dealers are liable to be quashed. Therefore, we quash those demand notices issued to the dealers in not following the procedure under section 12 of the Act for rectification of the order of assessment with the demand of interest enhancing the total amount of tax payable by the dealer for the particular period. However, the assessing authority may take up rectification proceeding in case of those affected dealers if those are not otherwise barred and if there is no other impediment under the Act and the Rules. We have already held that the provisions of the Act and the Rules cannot have any retrospective operation and it would only be effective on and from the date it was notified in the Assam Gazette on 25.6.69 and not from J.1.68. We have already held that the provisions of the Act and the Rules cannot have any retrospective operation and it would only be effective on and from the date it was notified in the Assam Gazette on 25.6.69 and not from J.1.68. Therefore, no interest would be leviable under the Rules in case; of those dealers to whom demand notices were issued for the period ending 31.3.68, 30.9.68 and 31.3.69 except the liabilities as imposed under section 22A of the Act. We also accordingly hold that the demand notices to the dealers asking them to pay interest as per demand notices without following the procedure as prescribed under section 12 of the Act are set aside and quashed. In the result all the petitions are disposed of in terms as aforesaid. We leave the parties to bear their own cost.