Code of Federal Regulations Title 26. Internal Revenue § 26.301.7701–6 Definitions;  person, fiduciary

(b) Fiduciary—(1) In general. Fiduciary is a term that applies to persons who occupy positions of peculiar confidence toward others, such as trustees, executors, and administrators. A fiduciary is a person who holds in trust an estate to which another has a beneficial interest, or receives and controls income of another, as in the case of receivers. A committee or guardian of the property of an incompetent person is a fiduciary.

(2) Fiduciary distinguished from agent. There may be a fiduciary relationship between an agent and a principal, but the word agent does not denote a fiduciary. An agent having entire charge of property, with authority to effect and execute leases with tenants entirely on his own responsibility and without consulting his principal, merely turning over the net profits from the property periodically to his principal by virtue of authority conferred upon him by a power of attorney, is not a fiduciary within the meaning of the Internal Revenue Code. In cases when no legal trust has been created in the estate controlled by the agent and attorney, the liability to make a return rests with the principal.