N.Y.C. Admin. Code § 12-117: § 12-117 Official oath.

Every person elected or appointed to any office in any agency of the city, shall within five days after notice of such election or appointment, take and subscribe, before the mayor, any judge of a court of record, the appointing officer or the city clerk, an oath or affirmation faithfully to perform the duties of his or her office. Such oath or affirmation shall be filed in the office of the city clerk.