Each national guard security officer or firefighter who is a member of the public employees retirement system is assessed and shall pay monthly four percent of the employee’s monthly salary. Member contributions increase by one-half of one percent of the member’s monthly salary beginning with the monthly reporting period of January 2014. Effective August 1, 2015, each national guard security officer or firefighter who is a participating member of the plan under this section becomes a participating member of the plan under section 54-52-06.4 and the board shall thereafter manage any account balance associated with those participating members under section 54-52-06.4. After July 31, 2015, a new eligible employee may not become a participating member of the plan under this section. The assessment must be deducted and retained out of the employee’s salary in equal monthly installments. The national guard security officer’s or firefighter’s employer shall contribute an amount determined by the board to be actuarially required to support the level of benefits specified in section 54-52-17. The employer’s contribution must be paid from funds appropriated for salary or from any other funds available for such purposes. If the security officer’s or firefighter’s assessment is paid by the employer under subsection 3 of section 54-52-05, the employer shall contribute, in addition, an amount equal to the required national guard security officer’s or firefighter’s assessment.