Section 6. (a) Every individual inhabitant of the commonwealth who receives or accrues during the taxable year Massachusetts gross income, as defined in section two of chapter sixty-two, in excess of eight thousand dollars shall make a return of such income.

Every nonresident, whose Massachusetts gross income, determined in accordance with section five A of chapter sixty-two, exceeds eight thousand dollars or the personal exemption to which he may be entitled under section three of chapter sixty-two, whichever is the lesser, and every partnership, association, or trust whose federal gross income, as defined in section one of chapter sixty-two, exceeds one hundred dollars, shall make a return of such income.

Every individual, not otherwise required to file a return under the foregoing provisions of this section, who is a resident for a portion of a twelve-month period beginning on the first day of a taxable year and a nonresident for a portion of the same twelve-month period and whose Massachusetts gross income, as defined in section two of chapter sixty-two, exceeds eight thousand dollars shall make separate returns as a resident and a nonresident of his income subject to taxation under chapter sixty-two.

A husband and wife may make a single return jointly of income taxes under chapter sixty-two, even though one of the spouses has neither income nor deductions, provided that their taxable years begin on the same day and either end on the same day or on different days solely because of the death of either or both. Such return shall be known as a joint return and shall include the income, exemptions and deductions of both spouses. Each spouse shall be jointly and severally liable for the entire tax.

(b) Every executor, administrator, trustee, guardian, conservator, trustee in bankruptcy, assignee for the benefit of creditors and receiver, other than a receiver of a business corporation, every fiduciary referred to in section twenty-five of chapter sixty-two and every other person receiving income taxable under chapter sixty-two which exceeds one hundred dollars, shall make an annual return of his taxable income. An executor or administrator shall file a return under this section if his decedent received any such amount not returned by the decedent as to which a tax under chapter sixty-two may still be assessed within the time limited by section twenty-six of this chapter. If a person has been appointed executor or administrator after January first in any year, the return of such income received by his decedent but not reported by him shall be due and shall be filed on or before the fifteenth day of the fourth month after the date of such appointment. Every such fiduciary intending to make final distribution of an estate or trust before the end of any year shall file immediately prior to such distribution a return under this section of all such income received by him and by his decedent during said year and prior to such distribution, and the taxes thereon shall become due and payable forthwith.

(c) Except as otherwise provided, returns under this section shall be made on or before the fifteenth day of the fourth month following the close of each taxable year.