(1) On or before October 1, 1997, returns itemizing any property made taxable by the preceding section shall be due, accompanied by the appropriate tax payment calculated as follows:

(a) The tax imposed by § 19-1102 shall be assessed at the rate of five mills on the value of taxable property on January 1, 1996.

(b) Such tax liability shall be offset by a credit equal to the amount previously paid by such taxpayer to the City of Philadelphia pursuant to the Act of June 17, 1913, P.L. 507, No. 335, as amended, with respect to the value of property on January 1, 1993, January 1, 1994, January 1, 1995, and January 1, 1996.

(2) The due dates for returns and payments set forth in this Section may be amended by the Revenue Department, by regulation, if necessary for administrative or other purposes.^[119]