(a) Every fiduciary, except receivers appointed by authority of law in possession of part only of the property of a taxpayer, shall make a return for the taxpayer for whom he acts, first, if the net income of such taxpayer is $1,500 or over, if single or if married and not living with husband or wife, or $3,000 or over, if married and living with husband or wife, or second, if the net income of such taxpayer, if an estate or trust, is $1,500 or over, or if any beneficiary is a taxpayer other than a resident of the state, which returns shall state specifically the items of the gross income and the deductions, exemptions and credits allowed by this chapter under such regulations as the Department of Revenue may prescribe, a return made by one or two or more joint fiduciaries and filed in the office of the Department of Revenue shall be a sufficient compliance with the above requirement. The fiduciary shall certify that he has sufficient knowledge of the affairs of such individual, estate or trust to enable him to make the return, and that the same is, to the best of his knowledge and belief, true and correct. Except as herein provided and as provided in Section 40-18-42, fiduciaries required to make returns under this chapter shall be subject to all provisions of this chapter which apply to taxpayers.

(b) Returns made on the basis of a calendar year shall be filed on or before April 15 following the close of such calendar year. Returns made on the basis of a fiscal year shall be filed on or before the fifteenth day of the fourth month following the close of such fiscal year. The Commissioner of Revenue or such person as may be in charge of the Department of Revenue may grant any reasonable extension of time for filing returns.