Revised Statutes of Missouri — Title X (Taxation and Revenue)
§ 143.271 RSMo — Period for computation of taxable income
1. For purposes of taxes imposed by sections 143.011 to 143.996 , a taxpayer's taxable year shall be the same as his taxable year for federal income tax purposes.
2. If a taxpayer's taxable year is changed for federal income tax purposes, his taxable year for purposes of the tax imposed by sections 143.011 to 143.996 shall be similarly changed. If a change in taxable year results in a taxable period of less than twelve months, the deductions allowed by sections 143.011 to 143.996 shall be prorated under regulations prescribed by the director of revenue.
Source: official text