(a) General rule. -- The expired provisions in subsection (j), section nine of this article, which previously exempted sales of tangible personal property to persons engaging in the activity of contracting, pursuant to a written contract with the United States, this state, or with a political subdivision thereof, or with a public corporation created by the Legislature or by another governmental entity pursuant to an act of the Legislature, for a building or structure, or improvement thereto, or other improvement to real property that is or will be owned and used by the governmental entity for a governmental or proprietary purpose, shall continue in force for:

(1) Tangible personal property purchased by a contractor on or after October 1, 1990, in fulfillment of a written contract for contracting, as defined in section two of this article, that was executed and legally binding on the parties thereto on or before September 15, 1990; or in fulfillment of a written contract entered into after said fifteenth day of September pursuant to a written bid for contracting that was made on or before said fifteenth day of September that was binding on the contractor, but only to the extent that the bid is subsequently incorporated into a written contract; and

(2) Tangible personal property purchased by a contractor on or after October 1, 1990, for consumption or use in fulfillment of a written contract for the construction of a new improvement to real property, the construction or operation of which was approved by a federal or state regulatory body prior to September 15, 1990, or pursuant to a federal grant awarded prior to said fifteenth day of September.

(b) Renewals and extensions. -- A renewal of any contract shall constitute a new contract for purposes of this section, and the date of entry into a contract renewal by the parties, the date or dates of tender of consideration and the time of performance of any contractual obligations under a renewed contract shall be treated as the dates for determining application of this section to the renewed contract. Extensions of time granted or agreed upon by the parties to a contract for performance of the contract or for tender of consideration under the contract shall not be treated as contract renewals. Contracts to which such extensions apply shall be treated under these transition rules as if the original contractual provisions for performance and tender of consideration remain in effect. For purposes of this section, the terms "contract" or "contracts", and "contract renewal" or "renewal" shall have the same meaning as defined in subsection (d), section eight-a of this article.