Mo. Rev. Stat. ยง 145.481
145.481 Tax return required when โ executor's duty.
145.481. Tax return required when โ executor's duty. โ A tax return with respect to the tax imposed by sections 145.011 to 145.995 shall be made:
(1) With respect to a resident, by every executor who is required to file a federal estate tax return;
(2) With respect to a nonresident, by every executor who is required to file a federal estate tax return if that part of the gross estate having a tax situs within the state of Missouri exceeds ten thousand dollars.
(L. 1980 S.B. 539) Effective 1-1-81