Idaho Code § 72-1431
Beginning October 1, 1978, there is hereby levied upon and shall be paid to the public employee retirement system board, in addition to other provisions of payment to the board, a contribution from each paid firefighter establishing the right to benefits under the provisions of chapter 14, title 72, Idaho Code, as follows:
The contribution shall be collected by the employer by deducting the amount of the contribution from the firefighter's wages or salary as and when paid. The contribution shall be remitted to the retirement board by the city or fire district employing the paid firefighter no later than five (5) days after each pay date. The average paid salary or wage or the individual firefighter's salary or wage, shall be calculated annually no later than the first day of September by the director, in the manner prescribed in section 72-1432, Idaho Code. The director shall notify each city and fire district of the amount of the contribution to be collected based on the average paid salary or wage or individual firefighter's salary or wage, as applicable, for all pay periods commencing on or after the first day of October.
Idaho Code § 72-1431