2006 New York Code - Office Hours.

 
    § 21. Office hours. Unless otherwise provided by law, the city offices
  shall be kept open for the transaction of business each day in the year,
  Sundays  and  legal  holidays excepted, from ten o'clock in the forenoon
  until four  o'clock  in  the  afternoon,  except  that  the  offices  of
  comptroller,  city  treasurer and the office for the collection of water
  rents, shall be kept open as aforesaid from ten o'clock in the  forenoon
  until  three  o'clock in the afternoon. The common council may from time
  to time direct any city office to be kept open at such  other  hours  as
  public convenience may require.