Section 7. (a) With respect to any period of insurance which is in effect for an active or retired employee and dependent there shall be withheld from each payment of salary, wages, other compensation, pension or retirement allowance, subject to the provisions of section nine A, fifty per cent of the premium for the insurance of the employee and his dependents and the governmental unit shall contribute the remaining fifty per cent of such premium. The governmental unit shall also contribute fifty per cent of any additional premium which may be required for coverage of an employee's dependent child who is nineteen years of age or over and mentally or physically incapable of earning his own living.

(b) If an employee is entitled to receive, during a calendar month, salary, wages or other compensation, and the premium has not been withheld from said salary, wages or other compensation, he may continue his insurance in effect by paying directly to the governmental unit the premium which would otherwise have been deducted from his salary or wages and said governmental unit shall contribute the remaining fifty per cent of the cost of the premium. If an employee is not entitled to receive salary, wages or other compensation for a calendar month, for purposes of this chapter, he shall be deemed to have been granted a leave of absence without pay, and shall make payment for the entire cost of his insurance to the governmental unit as aforesaid, and there shall be no contribution by the governmental unit for such employee's insurance. If an employee is not entitled to receive salary, wages or other compensation for any calendar month, due to illness of such employee and not because of illness of his immediate family, for purposes of this chapter he shall be deemed to have been granted sick leave without pay, and subject to the rules and regulations of the appropriate public authority, said employee shall make payment for fifty per cent of the cost of his insurance to the treasurer of the governmental unit, and such governmental unit shall contribute the remaining fifty per cent of said premium.

(c) All amounts withheld from an employee's salary, wages or other compensation as provided in paragraph (a) of this section and all amounts paid by an employee as provided in paragraph (b) of this section and all amounts withheld from retired employees as retirement allowances under the provisions of section nineteen A of chapter thirty-two together with the contribution of the governmental unit as provided in paragraph (a) shall be paid by the treasurer of the governmental unit to the carrier or carriers entitled to the premium.