In the case of residences owned or leased by the Government the addition to be made for meeting ordinary and special charges of maintenance and repairs and municipal and other taxes in the nature of house or property tax payable by the Government shall be as follows:(a)For ordinary maintenance and repairs and municipal and other taxes in the nature of house or property tax payable by the Government the rent shall be one-twelfth of the amount estimated as the annual cost of the ordinary repairs, together with a proportional share of the expenditure on repairs that may be required quadrennially or at other intervals, plus one-twelfth of the amount of all municipal and other taxes in the nature of house or property tax payable in a year by the Government. Municipal and other taxes not in the nature of house or property tax which by agreement or local rule or custom are levied on the occupant and not on the owner shall be payable by the occupant in addition to the rent payable under these rules. Such taxes will not be taken into account in the estimate of the executive engineer. Where any such tax is payable by the Government it shall be recovered from the occupant along with the rent at a monthly rate of one twelfth of the amount payable in a year by the Government provided that the recovery of the tax, like that of rent, will be made from him only for the period during which he is or is deemed to be in occupation of the residence.(b)For special maintenance and repairs the monthly rent shall be determined on an estimate of the life of each class of work in the building.(c)For service installations (water-supply, sanitary, heating and electrical installations the rent shall be increased by 4 ½ per cent and 5 per cent of the capital cost, as distributed below, and shall be one-twelfth per mensem of the total amount thus arrived at-
