Mo. Rev. Stat. § 143.331: Resident estate or trust defined.

A "resident estate or trust" means:

(1) The estate of a decedent who at his or her death was domiciled in this state;

(2) A trust that:

(a) Was created by will of a decedent who at his or her death was domiciled in this state; and

(b) Has at least one income beneficiary who, on the last day of the taxable year, was a resident of this state; or

(3) A trust that:

(a) Was created by, or consisting of property of, a person domiciled in this state on the date the trust or portion of the trust became irrevocable; and

(b) Has at least one income beneficiary who, on the last day of the taxable year, was a resident of this state.