(b) There is hereby imposed in the city of Mount Vernon a tax on each deed by which any real property is conveyed (measured by the consideration or value of the interest or property conveyed) at a rate not to exceed one percent of such consideration or value with respect to all conveyances, provided that such city may allow deductions for any liens on such interest or property and may also allow an exemption not in excess of one hundred thousand dollars on the consideration or value of the interest or property conveyed. Provided, further, that such taxes shall not apply if the contract for any such conveyance was made prior to September first, nineteen hundred eighty-four. Such taxes may be imposed on any conveyance or transfer of real property or interest therein by deed where the real property is located in such city regardless of where transactions, negotiations, transfers of deeds or other actions with regard to the transfer or conveyance take place, subject only to the restrictions contained in section twelve hundred thirty. The payment of, and the filing of a return relating to, any such taxes may be required as a condition precedent to the recording of a deed.