Mo. Rev. Stat. § 143.481: Persons required to make returns of income.

An income tax return with respect to the tax imposed by sections 143.011 to 143.996 shall be made by the following:

(1) Every resident individual who has a Missouri adjusted gross income of one thousand two hundred dollars or more, or a greater amount as prescribed by the director of revenue and who is required to file a federal income tax return;

(2) Every nonresident individual who has a Missouri nonresident adjusted gross income (Missouri adjusted gross income derived from sources within this state) of six hundred dollars or more, or a greater amount as prescribed by the director of revenue and who is required to file a federal income tax return;

(3) Every resident estate or trust which is required to file a federal income tax return;

(4) Every nonresident estate which has gross income of six hundred dollars or more for the taxable year from sources within this state;

(5) Every nonresident trust which for the taxable year has from sources within this state, either:

(a) Any taxable income; or

(b) Gross income of six hundred dollars or more regardless of the amount of taxable income;

(6) Every corporation which:

(a) Is not an exempt corporation described in subsection 2 of section 143.441;

(b) Is required to file a federal income tax return; and

(c) Has gross income from sources within this state of one hundred dollars or more.