(1) The amount of tax determined under section 10 or 11 with the modification. if any, made under section 15 or in any appeal under section 16 or revision under section 19, shall remain in force- (a) for a period of 27four years from the date of commencement of the Rajasthan Urban Land Tax (Amendment) Act, 1973, or (b) for such further period not exceeding 28twenty years as the Government may direct. (2) After the expiration of the period of four years referred to in clause (a) of sub-section (1) the Government may, and after the expiration of the further period referred to in clause 9b) of sub-section (1), the Government shall, direct revision of the tax. (3) All the provisions of this Act, shall as far as may be apply to the determination of the tax in pursuance of a direction under sub-section (2) as they apply to the determination of tax for the first time after the commencement of the Rajasthan Urban Land Tax (Amendment) Act, 1973. (4) For the purpose of revision of the tax under sub-sections (2) and (3)- (a) the reference in section 4 and in clause 9a) of sub-section (1), to the date of commencement of the Rajasthan Urban Land Tax (Amendment) Act, 1973, shall be construed as a reference to the 1st day of April, of the year in which the direction under the said sub-section is issued; and (b) the period of ninety days referred to in section 7 shall be computed from the date on which such direction is issued. (5) Any direction for revision issued under sub-section (2) shall have effect prospectively and shall have no effect on past cases, where returns have been filed or in 26 Explanation in sub sc(1) of sc 13 of principal act, added at the end. published in offical Gazette 17 may, 1995. 27 four year substituted by three years vide finance act no. 11/2000 dated 10.05.2000 28 by amendment act no. 7/1992 (expression fifteen years subsituted by word twenty years. which the proceedings of assessment, amendment of assessment, appeal or revision under the provisions of this Act are pending on the date of coming into force of the direction issued under sub-section (2) and the proceedings of assessment, amendment in assessment, appeal or revision in such cases shall be continued, finalized, disposed of, ordered ordetermined in accordance with the provisions of this Act as in force before the date of enforcement of the revision of tax under sub-section (2) and for removal of doubts it is clarified that with effect from the date of enforcement of the direction issued under sub- section (2), the revision of tax under sub-section (2) shall also have effect on aforesaid cases prospectively.