Mo. Rev. Stat. § 136.405: Annual return defined — the filing of amended return after certain date not to be included.

The phrase "annual returns filed following the close of such fiscal year" , as used in Article X, Section 18, shall mean the last timely income tax returns which are filed and paid by the following June thirtieth. Amended returns filed after June thirtieth shall not be included in calculating the pro rata distribution amounts pursuant to Article X, Section 18, Paragraph (b). Returns filed for any part of a year shall be included.