If the successful bidder or offeror must undertake additional work due to the enactment of new or the amendment of existing statutes, rules or regulations occurring after the submission of the successful bid or proposal, the government agency shall issue a change order setting forth the additional work that must be undertaken, which shall not invalidate the contract. The cost of a change order to the government agency shall be determined in accordance with the provisions of the contract for change orders or force accounts, or, if there is not a provision set forth in the contract, then the cost to the government agency shall be the costs to the contractor for wages, labor costs other than wages, wage taxes, materials, equipment rentals, insurance and subcontracts attributable to the additional activity plus a reasonable sum for overhead and profit. Additional costs to undertake work not specified in the invitation for bids or requests for proposals shall not be approved unless written authorization is given the successful bidder or offeror prior to its undertaking the additional activity.