1. (a) Except as otherwise provided in this Subchapter, a person required to make and file a New York State income tax return under the provisions of this Subchapter must, without assessment, notice or demand, pay in full any income tax due thereon to the New York State Department of Taxation and Finance on or before the due date fixed for filing such return. As to extensions of time for payment of income tax allowed in connection with extensions of time to file a New York State income tax return, see Part 157 of this Article.
2. (b) Where any payment of income tax required to be made within a prescribed period or on or before a prescribed date is mailed in accordance with the provisions of section 2399.2 of this Title, such payment, if not dishonored upon presentment, will be deemed timely made.
3. (c) See section 2399.3 of this Title when the last day prescribed (including any extensions of time) for making any payment falls on a Saturday, Sunday or a legal holiday in the State of New York.

Tax Law, §§ 652, 691