(a) Where any return or payment of tax required to be filed or 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 return or payment (if not dishonored upon presentment) will be deemed timely filed and timely made.

(b) Returns filed or payments made prior to the last date prescribed for filing or paying shall be considered filed and made on such last date.

(c) When the last date prescribed for filing a return or for making a payment falls on a Saturday, Sunday or legal holiday in the State of New York see section 2399.3 of this Title.