Idaho Code § 54-5208
A contractor who is not registered as set forth in this chapter, unless otherwise exempt, shall be denied and shall be deemed to have conclusively waived any right to place a lien upon real property as provided for in chapter 5, title 45, Idaho Code. This section shall not operate as a denial of lien rights for any subcontractor or independent contractor who is duly registered in accordance with this chapter and who is performing services at the direction of another contractor, nor shall it operate as a denial of lien rights for any employee of any contractor who is not duly registered, or for any supplier of materials to such unregistered contractor, so long as such subcontractor, independent contractor, employee or supplier did not have actual knowledge that such contractor was not duly registered, or who reasonably believed that such contractor was duly registered.
Idaho Code § 54-5208