Iowa Code § 331.215: Compensation and expenses.

1. The supervisors shall receive an annual salary or per diem compensation as determined under section 331.907. The annual salary or per diem shall be full payment for all services rendered to the county except for reimbursement for mileage and other expenses authorized in subsection 2.

2. A supervisor is entitled to reimbursement for mileage expenses incurred while engaged in the performance of official duties at the rate specified in section 70A.9. The total mileage expense for all supervisors in a county shall not exceed the product of the rate of mileage specified in section 70A.9 multiplied by the total number of supervisors in the county times ten thousand. The board may also authorize reimbursement for mileage and other actual expenses incurred by its members when attending an educational course, seminar, or school which is related to the performance of their official duties.