Idaho Code § 20-209A: Computation of term.

When a person is sentenced to the custody of the board of correction, his term of confinement begins from the day of his sentence. The time during which the person is voluntarily absent from the penitentiary, jail, facility under the control of the board of correction, or from the custody of an officer after his sentence, shall not be estimated or counted as a part of the term for which he was sentenced.