§239-4 Returns. Each public service company, on or before the twentieth day of the fourth month following the close of the taxable year, shall file with the office of the department of taxation for the district within which the principal office of the public service company is maintained a return in such form as the department may prescribe, 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 the same as if no public utility business were done. [L 1932 2d, c 43, §3; RL 1935, §2142; RL 1945, §5673; RL 1955, §126-4; am L 1957, c 34, §22; am L Sp 1959 2d, c 1, §16; am L 1963, c 147, §2(d); am L 1967, c 37, §1; HRS §239-4; am L 1991, c 25, §1]