Idaho Code § 15-7-105
A foreign corporate trustee is required to qualify as a foreign corporation doing business in this state if it maintains the principal place of administration of any trust within the state. A foreign cotrustee is not required to qualify in this state solely because its cotrustee maintains the principal place of administration in this state. Unless otherwise doing business in this state, local qualification by a foreign trustee, corporate or individual, is not required in order for the trustee to receive distribution from a local estate or to hold, invest in, manage or acquire property located in this state, or maintain litigation. Nothing in this section affects a determination of what other acts require qualification as doing business in this state.
Idaho Code § 15-7-105