Idaho Code § 31-5207: Election of additional commissioners — All members of commission may be elected to four year terms.

(1) If the size of the board of county commissioners is increased, the additional commissioners shall be elected at the following general election.

(2) Except as provided in subsection (3) of this section, the additional members shall be elected for a term of two (2) years, with the allotment of the four (4) year term between the entire commission to proceed in numerical rotation in accordance with the provisions of section 31-703, Idaho Code.

(3) Notwithstanding the provisions of section 31-703, Idaho Code, or any other provision of law to the contrary, the petition or resolution to adopt the optional form of government provided in this chapter may provide that all members of the board of county commissioners for the county be elected to serve terms of four (4) years. If approved by the electors, the commissioner for each additional district shall be elected to a term of four (4) years and commissioners for existing districts shall be elected to a term of four (4) years upon the expiration of the commissioner’s current term of office.