(a) An income tax return with respect to the tax imposed by this chapter shall be filed with the commissioner by every:
(1) Resident who is required to file a federal income tax return for the taxable year;
(2) Nonresident who has federal gross income from sources within this state;
(3) Resident estate or trust that is required to file a federal income tax return;
(4) Nonresident estate or trust that has federal gross income from sources within this state; and
(5) Resident or nonresident who has taxable income subject to Georgia income tax for the taxable year who does not have taxable income subject to federal income tax for the same taxable year.
(b) The commissioner may require each taxpayer by regulation to file with the return required by this chapter a copy of all or any part of the taxpayer's federal income tax return for the corresponding period.