On or before the first day of January of each year the board of trustees shall certify to the board of education, the board of trustees and the board of regents, and to the state of Missouri with respect to the contribution for members employed by these employers, the amount which will be paid to the retirement system on or before December thirty-first of that year. On or before the first day of January of each year the board of trustees shall certify to charter schools and to the state of Missouri with respect to the contribution of members employed by these employers, the amount which will be paid to the retirement system on a monthly basis beginning January first of that year. The amount so certified shall be included by the employers in their annual budget estimates.