Mo. Rev. Stat. § 408.083: Credit contracts, prepayment before maturity, computation of interest.

Notwithstanding any other provision of law to the contrary, all credit contracts with interest or time price differential calculated on an add-on basis entered into after August 28, 2002, the proceeds of which are used for personal, family or household purposes, shall provide that the amount of interest or time price differential earned upon prepayment in full will be computed on the basis of the rate or rate formula originally contracted for on the actual unpaid principal balances for the time actually outstanding.