Idaho Code § 67-1023

All persons having claims against the state must exhibit the same, with the evidence in support thereof, to the state controller, to be examined, settled and allowed by the board of examiners, within two (2) years after such claims shall accrue, and not afterward. In all suits brought in behalf of the state, no debt or claim must be allowed against the state as a set-off but such as have been exhibited to the state controller, and allowed or disallowed by the board of examiners except only in cases where it is proved to the satisfaction of the court that the defendant, at the time of the trial, is in possession of vouchers which he could not produce to the state controller, or that he was prevented from exhibiting the claim to the state controller by absence from the state, sickness, or unavoidable accident. No claim which is not provided for by law shall be examined or set off.