N.Y. Comp. Codes R. & Regs. tit. 4 § 6.3
No officer or employee regularly employed in a position in the classified service in any State department or agency shall, while continuing to hold such position, accept appointment or employment in any other position or title, or in any capacity whatsoever, on a full-time or part-time basis, either in the classified or unclassified service, in another Sate department or agency, or in the Legislature or the judiciary, for which employment compensation or salary is payable, without the previous consent in writing of the head of the department or agency in which he is regularly employed. Such written consent shall be required, in each case, for each such additional appointment or employment accepted or undertaken by such officer or employee, and a copy thereof shall be filed by the head of the department or agency in the office of the Comptroller. A willful violation of the provisions of this section shall be deemed sufficient cause for disciplinary action, including removal. This section shall not apply to the employment by the Department of Civil Service of an officer or employee of another department or agency of the State to act as an examiner in a civil service examination or examinations or to prepare or review test questions, appeals from examination ratings or other examination materials.
N.Y. Comp. Codes R. & Regs. Tit. 4 § 6.3