§ 143.441 RSMo — Corporation defined — corporate tax inapplicable, when

1. The term "corporation" means every corporation, association, joint stock company and joint stock association organized, authorized or existing under the laws of this state and includes:

(1) Every corporation, association, joint stock company, and joint stock association organized, authorized, or existing under the laws of this state, and every corporation, association, joint stock company, and joint stock association, licensed to do business in this state, or doing business in this state, and not organized, authorized, or existing under the laws of this state, or by any receiver in charge of the property of any such corporation, association, joint stock company or joint stock association;

(2) Every railroad corporation or receiver in charge of the property thereof which operates over rails owned or leased by it and every corporation operating any buslines, trucklines, airlines, or other forms of transportation, including qualified air freight forwarders, operating over fixed routes owned, leased, or used by it extending from this state to another state or states. For purposes of this subdivision, "qualified air freight forwarder" means a taxpayer who meets all of the following requirements:

(a) The taxpayer is primarily engaged in the facilitation of the transportation of property by air;

(b) The taxpayer does not itself operate the aircraft; and

(c) The taxpayer is in the same affiliated group as an airline;

(3) Every corporation, or receiver in charge of the property thereof, which owns or operates a bridge between this and any other state; and

(4) Every corporation, or receiver in charge of the property thereof, which operates a telephone line or lines extending from this state to another state or states or a telegraph line or lines extending from this state to another state or states.

2. The tax on corporations provided in subsection 1 of section 143.431 and section 143.071 shall not apply to:

(1) A corporation which by reason of its purposes and activities is exempt from federal income tax. The preceding sentence shall not apply to unrelated business taxable income and other income on which chapter 1 of the Internal Revenue Code imposes the federal income tax or any other tax measured by income;

(2) An express company which pays an annual tax on its gross receipts in this state;

(3) An insurance company which is subject to an annual tax on its gross premium receipts in this state;

(4) A Missouri mutual or an extended Missouri mutual insurance company organized under chapter 380 ; and

(5) Any other corporation that is exempt from Missouri income taxation under the laws of Missouri or the laws of the United States.