Mo. Rev. Stat. § 143.175
1. For all tax years beginning on or after January 1, 2020, for purposes of calculating the Missouri taxable income as required under section 143.011, a percentage of the income received by any person as salary or compensation:
(3) For all tax years beginning on or after January 1, 2025, in the form of a bonus from the National Guard or a reserve component of the United States Armed Forces for joining, reenlisting, or for any other reason;
and to the extent that such income is included in the federal adjusted gross income, may be deducted from the taxpayer's Missouri adjusted gross income to determine such taxpayer's Missouri taxable income. If such person files a combined return with a spouse, a percentage of any military income received while engaging in the performance of National Guard or reserve military duty may be deducted from their Missouri combined adjusted gross income. Such military income shall be deducted as follows:
(L. 2018 S.B. 573, A.L. 2024 S.B. 912)