Idaho Code § 63-907
The county treasurer shall, on or before the first day of January in the succeeding year, enter all delinquent taxes on the property rolls. Such entries shall be dated as of the first day of January and shall have the force and effect of a sale to the treasurer as grantee in trust for the county, for all property entered upon the property roll on which first installment of the taxes has not been paid. The settlement date shall be as of the close of business on the December due date of the preceding year.
The county treasurer shall, on or before the first day of July in the succeeding year, make delinquency entries to be dated as of the first day of January in the year the taxes fall delinquent for all property entered upon the property roll on which the second installment of the taxes have not been paid. The settlement date shall be as of the close of business on the June due date of the current year.
Idaho Code § 63-907