Each public service company, on or before the twentieth day of the fourth month following the close of the taxable year, shall file a return in the form and manner prescribed by the department, showing its taxable gross income for the preceding taxable year. In case any public service company engages in lines of business other than its public service company business, the receipts therefrom shall not be subject to tax under this chapter, but the same tax liabilities shall attach to the public service company on account of the other lines of business as would exist if no public service company business were engaged in. In the case of a public utility subject to the rate of tax imposed by section 239-5(a) or (b), if the public utility engages in lines of business other than its public utility business the real property used in connection with the other lines of business shall be taxed, in accordance with the applicable county tax ordinance, the same as if no public utility business were done. In the case of a public utility remitting payments to a county of a portion of the revenues generated from the tax imposed by section 239-5(a), the public utility shall also file with the director of finance of the county to which such payment is paid, a statement showing all gross income from the public utility business upon which the tax is calculated and the allocation of that gross income among the counties.