Sec. 4.05. MUNICIPAL CONTRIBUTIONS. (a) Except as provided by Subsection (a-1) of this section, a municipality to which this Act applies shall pay into the fund an amount equal to double the sum total of all member contributions made in accordance with Section 4.04 of this Act.

(a-1) For a member who participates in the fund for the first time after September 30, 2003, and before October 1, 2005, a municipality is not required to pay an amount under Subsection (a) of this section into the fund for the member before the 61st day after the date the member becomes a participant in the fund.

(b) The payments into the fund by the municipality, both as to deductions and double-matching amounts, shall be made on the same day the contributions are deducted from the members' total salary.

(c) Any donations made to the fund and all amounts received from any source for the fund shall be deposited in the fund at the earliest opportunity.

(d) The municipality's double-matching amount under this section is in place of all other payments previously required by law to be made by the municipality.

(e) The municipal contribution and retirement annuities are a part of the compensation for services rendered to the municipality. This Act is of the essence of the contract of employment and appointment of the fire fighters and police officers of a municipality to which this Act applies.