(1) Chartered as a nonprofit general welfare corporation under the laws of Tennessee for the purpose of providing fiduciary services to mentally or physically disabled persons;
(2) Exempt from federal taxation under 26 U.S.C. § 501(c)(3); and
(3) Approved by the commissioner of mental health and substance abuse services or the commissioner of intellectual and developmental disabilities as providing a necessary service that is not otherwise generally available for those persons.