26 USC 7804 - Other personnel

(a) Appointment and supervision 
Unless otherwise prescribed by the Secretary, the Commissioner of Internal Revenue is authorized to employ such number of persons as the Commissioner deems proper for the administration and enforcement of the internal revenue laws, and the Commissioner shall issue all necessary directions, instructions, orders, and rules applicable to such persons.
(b) Posts of duty of employees in field service or traveling 
Unless otherwise prescribed by the Secretary
(1) Designation of post of duty 
The Commissioner shall determine and designate the posts of duty of all such persons engaged in field work or traveling on official business outside of the District of Columbia.
(2) Detail of personnel from field service 
The Commissioner may order any such person engaged in field work to duty in the District of Columbia, for such periods as the Commissioner may prescribe, and to any designated post of duty outside the District of Columbia upon the completion of such duty.
(c) Delinquent Internal Revenue officers and employees 
If any officer or employee of the Treasury Department acting in connection with the internal revenue laws fails to account for and pay over any amount of money or property collected or received by him in connection with the internal revenue laws, the Secretary shall issue notice and demand to such officer or employee for payment of the amount which he failed to account for and pay over, and, upon failure to pay the amount demanded within the time specified in such notice, the amount so demanded shall be deemed imposed upon such officer or employee and assessed upon the date of such notice and demand, and the provisions of chapter 64 and all other provisions of law relating to the collection of assessed taxes shall be applicable in respect of such amount.