Mo. Rev. Stat. § 169.587: Benefits exempted from taxation and creditors — benefits not assignable.

Any retirement allowance, benefit, funds, property, or rights created by, or accruing to any person under the provisions of this chapter, are hereby made and declared exempt from any tax of the state of Missouri or any political subdivision or taxing body thereof and shall not be subject to execution, garnishment, attachment, writ of sequestration, or any other claim whatsoever and shall be unassignable.