Idaho Code § 41-5603

An insurer that fails to pay, request additional information or documentation or deny a claim from a beneficiary, practitioner or facility within the time periods established in this chapter shall pay interest at the contract statutory rate pursuant to section 28-22-104, Idaho Code, on the unpaid amount of a claim that is determined to be due and owing. The interest shall accrue from the date payment was due, pursuant to the provisions of this chapter, until the claim is paid. Payment of any interest amount of less than four dollars ($4.00) shall not be required. Insurers may add any interest due to a future payment to the beneficiary, practitioner or facility.