Idaho Code § 31-303
The county tax collector of the divided county shall immediately, after the passage and approval of this chapter, proceed to make and certify to a transcript of so much of the tax rolls of his office as show taxes levied and assessed against persons, firms, associations, corporations, real and personal property in the territory included in the newly-created county, and unpaid at the time this chapter goes into effect, and as soon as such transcript is completed, the same shall be delivered to the tax collector of the newly-created county and become thenceforth the property of such newly-created county and the official record thereof, with the same force and effect as the original tax roll, and shall be authority for the tax collector of the newly-created county to collect such unpaid taxes, both real and personal, in any manner authorized by law.
Idaho Code § 31-303