Miss. Code Ann. § 27-7-31: Miss. Code Ann. § 27-7-31

(1) Every resident individual (whether single or married) and every nonresident individual (whether single or married) owning or selling property, earning income, or doing business in the State of Mississippi, having a gross income for the taxable year in excess of the exemptions allowed hereunder, plus the standard deduction, shall make a return, which shall contain an oath or be verified by a written declaration that it is made under the penalties of perjury, stating specifically the items of gross income and the deductions and exemptions allowed by this article. The commissioner may prescribe methods by which the taxpayer may make such oath or declaration other than by writing.

(2) Married individuals may elect to file either separate or joint returns. In any case where a husband and wife file a joint return, and one spouse is granted relief from liability under 26 USCS 6015 , such spouse shall be granted comparable relief from liability for the tax imposed under this chapter.

(3) If the taxpayer is unable to make his own return, the return shall be made by a duly authorized agent or by the guardian or other person charged with the care of the person or estate of such taxpayer.