Judgment 1. Leave granted. 2. In 1970, an agreement was entered into between Calcutta Municipal a Corporation and Calcutta Port wherein annual valuation was fixed on rental method. That agreement was in force for a long time. In 1998, the municipal authority felt that there should be revision of annual valuation. Accordingly, special notices were issued in that year in which the Corporation suggested alteration in the valuation based on the change in the method of valuation from rental method to cost method. The municipal authorities insisted upon enhanced rate/annual valuation to be given effect to from the first quarter of 1990-1991 and thereafter at a further enhanced rate from the first quarter of 1996-1997. Calcutta Port did not agree to the said proposal. They objected to the effect being given to the said alteration from 1990-1991 and from 1996-1997. 3. Ultimately, the Hearing Officer passed an order on 21-11-2001 making alteration in the valuation with effect from the first quarter of 1990-1991 and the first quarter of 1996-1997. This was challenged before the Calcutta High Court. The learned Single Judge allowed the writ petition vide judgment dated 19-6-2000 (sic) which was affirmed by the Division Bench. Hence this civil appeal. 4. At the time of notice, this Court limited the question to the revision with effect from the first quarter of 1996-1997. Before analysing various sections of the Calcutta Port Act, 1890 (for short "the Act"), we may state that conceptually there is a difference between chargeability, valuation and computation of liability. These three concepts are required to be kept in mind while interpreting various provisions of the Act. 5. Part IV of the Act deals with assessment of the property of the Commissioners. Section 59 falls in Part IV. It, inter alia, states that for the purposes of municipal assessment, the annual value of the property vested in the Commissioners shall be ascertained on the cost method. In fact, the reading of various provisions of Part IV of the Act indicates that as a general rule, annual value of the property vested in the Commissioners is required to f be ascertained on cost basis and not on rental basis. That is the reason why in Section 59(1) the words used are "the aggregate expenditure incurred in the construction of all docks". That is the reason why in Section 59(1) the words used are "the aggregate expenditure incurred in the construction of all docks". However, there is a proviso which finds place in Section 66-A(1) which, inter alia, states that the cost method may not be applicable in a case where an agreement is arrived at between the Commissioners and the Corporation providing for a different basis of 9 valuation e.g. rental value. 6. Payability is different from valuation. Section 61 of the Act provides for payment of taxes in four quarterly instalments. We are not basically concerned with the question of payment. In this case, we are concerned with fixation of annual value. 7. Under Section 65(2) of the Act, it is expressly made clear that Sections h 59 to 63 shall apply to valuations. Section 66-A deals with method of calculating annual value of a building which is let out to tenants and any building or structure erected thereon by such tenants. In such cases, the rate at which the annual value shall be calculated is provided for. We are also not basically concerned with the rate. Under Section 66-B, it is, inter alia, provided that buildings falling under Section 66-A may be valued annually at the discretion of the Corporation, however, the unrevised valuation shall remain in force from year to year until revaluation. 8. Under Section 66-F of the Act, we have the procedure for revaluation. Under Section 66-F(2) it is, inter alia, stated that if the revised valuation exceeds the previous valuation, the Corporation shall include in the special notice in Section 66-K(3) full details of the amount of such valuation. This sub-section indicates that if the revised valuation leads to enhancement of tax, as compared to the previous valuation, then the procedure under Section 66-F needs to be followed. This is the basic scheme of valuation and assessment under the Act. 9. The heart of the controversy revolves around Sections 66-F(2) and 66-K of the Act which we quote herein below: "66-F. (2) If the valuation so made exceeds the previous valuation, the Corporation of Calcutta shall include in the special notice provided for in Section 66-K(3) full details of the amount of such valuation. 9. The heart of the controversy revolves around Sections 66-F(2) and 66-K of the Act which we quote herein below: "66-F. (2) If the valuation so made exceeds the previous valuation, the Corporation of Calcutta shall include in the special notice provided for in Section 66-K(3) full details of the amount of such valuation. * * * 66-K. Assessment, assessment book and special notice.-(l) The valuation so made by the Corporation of Calcutta, subject to such alterations as may, from time to time thereafter, be duly made, shall be entered in a book, to be called the assessment book, and to be kept at the office of the Corporation, and in the same form, as far as may be, as the rent register of the Commissioners. (2) A copy of such book and of all entries therein, as modified from time to time, shall be supplied to the Commissioners, and shall be open to inspection between the hours of 11 a.m. and 5 p.m. at the head office of the Commissioners. (3) A special notice, including an extract from the assessment book showing the valuation of each building or structures, and stating the time within which an objection shall be lodged, shall, on the completion of the valuation under Sections 66-A to 66-F (both inclusive), be given by the Corporation to the owner of such building or structure. (4) The assessment calculated on the said valuation shall, subject to such alterations as aforesaid, be deemed to be the amount payable during the whole period for which the valuation is in force; and this period shall be calculated from the commencement of the quarter next succeeding that in which any alterations as aforesaid shall have been made; and until such date, the old valuation shall continue in force, notwithstanding that the period for which it was made may have expired." 10. Section 66-K refers to assessment, assessment book and special notice. Section 66-K(l) states that the valuation made by the Corporation, subject to such alterations as may, from time to time thereafter, be duly made, shall be entered in the assessment book. Under Section 66-K(3), a special notice showing the valuation of each building and stating the time within which the objection shall be lodged on completion of the valuation under a Sections 66-A to 66-F shall be given to the owner of such building. Under Section 66-K(3), a special notice showing the valuation of each building and stating the time within which the objection shall be lodged on completion of the valuation under a Sections 66-A to 66-F shall be given to the owner of such building. Under sub-section (4) it is, inter alia, stated that the assessment calculated on the valuation in Section 66-K(3) shall, subject to such alterations as aforestated, be deemed to be the amount payable during the whole period for which the valuation is in force; and this period shall be calculated from the commencement of the quarter next succeeding in which any alteration in the b valuation is made; and until such date, the old valuation shall continue in force, notwithstanding the period for which it was made may have expired. 11. A reading of sub-sections (3) and (4) of Section 66-K therefore makes it very clear that in cases where the basis of valuation is altered, let us say from rental to cost method, which leads to increase in taxes, the alteration in the valuation finally confirmed by the Hearing Officer after hearing the c parties, shall operate from the quarter next succeeding that quarter in which the alteration is made and till such time the previous valuation shall continue. Hence the impugned alteration will not operate with effect from 1996-1997 as contended by the Corporation. 12. Before concluding, we may state that the assessment under the Act is being administered by the officers/authorities of the Corporation under the d Calcutta Municipal Corporation Act. The scheme of assessment and valuation under that Act is quite different from the scheme of assessment and valuation under the Calcutta Port Act. The Port Act is applicable to the properties vested in the Commissioners. The two Acts operate in different spheres. 13. In the circumstances, we find no merit in this civil appeal. The same e is, accordingly, dismissed. No order as to costs.