Mo. Rev. Stat. § 376.2053

An insurer that has not engaged in any asymmetric conduct prior to January 1, 2018, shall not be required to comply with the requirements of sections 376.2050 to 376.2053 with respect to any policies, contracts, or retained asset accounts that are issued and delivered in this state and that are issued or entered into prior to January 1, 2018; provided, however, that an insurer, regardless of whether it has engaged in asymmetric conduct, shall comply with the requirements of sections 376.2050 to 376.2053 for all policies, annuities, or retained asset accounts that are issued and delivered in this state and that are issued or entered into on or after January 1, 2018.