Save as otherwise provided in this Act, the base rate of property tax on buildings in New Delhi shall be between a minimum of ten per cent. and a maximum of twenty per cent. of the annual values of such buildings as may be specified by the Council from time to time:
Provided that the Council may, at any time, specify fixed rates between the minimum and the maximum rates of tax as aforesaid for different areas or for different groups of buildings in such areas:
Provided further that the Council may also introduce graduated rates of tax within the minimum and the maximum rates of tax as aforesaid on the basis of straight line system or any other system as may be specified by the Council.
Explanation.—For the purposes of this section and section 61E, “Straight line system” means the system in which the rate of tax is equivalent to the annual value of a property (X) divided by the minimum annual value (X1) and Y being added to the quotient so arrived, Y being the difference between the maximum rate of tax and the quotient of maximum (X2) and minimum (X1) annual values.