Mo. Rev. Stat. § 143.461 (2026)

  143.461.  Elective division of income. — 1.  A corporation shall elect to determine income applicable to this state by multiplying the total income from all sources by the fraction determined in the manner in section 143.451 for all tax years ending on or before December 31, 2019, and for all tax years beginning on or before January 1, 2020, in the manner set forth in section 143.455; first, by filing written notice with the director of revenue on or before the due date of the return (including extensions of time) of the taxpayer's election, or, second, by failing to keep its books and records in such manner as to show the income applicable to this state, including gross income and deductions applicable thereto.

  2.  If the corporation shall keep its books and records so as to show the income applicable to this state by any other method of allocation between this state and other states, including gross income and deductions applicable thereto, and such method shows the income applicable to this state, including gross income and deductions applicable thereto, then it may, on or before sixty days before the end of any taxable year, petition the director of revenue, in writing, to be permitted in its return required to be filed to apportion to this state according to the method shown by such books or records.  If the director of revenue finds that such method does show the income applicable to this state including gross income and the deductions applicable thereto, he or she shall notify the corporation, at least thirty days prior to the last day on which such corporation's return for that taxable year is to be filed, that it may use that method for the shorter of five years or as long as such method shows the income applicable to this state, including gross income and deductions applicable thereto.

  3.  The corporation shall cease using such method after the shorter of five years or whenever the director of revenue finds and notifies such corporation on or before ninety days before the end of the taxable year, that such method does not so show.  Upon and after such expiration or revocation the corporation shall be permitted to petition to use the same or another method of allocation that will show such income including gross income and deductions applicable thereto as though no petition had ever been filed.

  4.  Failure, after a method has expired or been revoked by the director of revenue, to submit a method which the director of revenue finds will show such income applicable to this state including gross income and deductions applicable thereto, on or before sixty days before the end of any taxable year, or failure to make a return on the basis, which has been approved by the director of revenue on petition of the corporation and which stands unrevoked or unexpired, shall constitute an election to accept the determination of income applicable to this state by multiplying the total income from all sources by the fraction determined in the manner set forth in section 143.451 for all tax years ending on or before December 31, 2019, and for all tax years beginning on or before January 1, 2020, in the manner set forth in section 143.455.