Mandatory amendment of Missouri income tax return after federal change
Missouri income and tax is determined starting with the federal adjusted gross income on the form 1040 filed with the IRS.
R.S.Mo. § 143.601 requires taxpayers whose federal returns are adjusted or audited to file an amended Missouri return within 90 days after the adjustments or audit has been completed or accepted.
R.S.Mo. § 143.601. Report of change in federal taxable income
If the amount of a taxpayer's federal taxable income reported on his federal income tax return for any taxable year is changed or corrected by the United States Internal Revenue Service or other competent authority, or as the result of a renegotiation of a contract or subcontract with the United States, the taxpayer shall report such change or correction in federal taxable income within ninety days after the final determination of such change, correction, or renegotiation, or as otherwise required by the director of revenue. Each such report shall state whether and wherein the determination is believed to be erroneous. Any taxpayer filing an amended federal income tax return shall also file within ninety days thereafter an amended return under sections 143.011 to 143.996, and shall give such information as the director of revenue may require. If a taxpayer does not file a federal income tax return under sections 143.011 to 143.996, then
(1) For purposes of the first sentence of this section, he shall be deemed to have filed a return indicating no taxable income, and
(2) For purposes of the third sentence of this section, his initial federal income tax return shall be deemed to be an amended return.
The director of revenue may by regulation prescribe such exceptions to the requirements of this section as he deems appropriate.