Mo. Rev. Stat. § 86.1400
The board of police commissioners shall cause to be deducted from the compensation of each member until retirement a percentage of such member's compensation, which shall not be less than five percent, as determined by the retirement board, as such member's contribution to the pension fund. The sum so deducted shall be paid by the board of police commissioners promptly after each payroll to the retirement board to be credited to the member's account. Every member shall be deemed to consent to the deductions made and provided for herein. The board of police commissioners shall certify to the retirement board on each payroll the amount deducted, and such amounts shall be paid into the pension fund and shall be credited to the individual pension account of the member from whose compensation such deduction was made.
§ 86.1400, RSMo