Me. Rev. Stat. tit. 23, § 8119

Because the accomplishment by the authority of the authorized purpose stated in this chapter is for the benefit of the people of the State and for the improvement of their commerce and prosperity and is the performance of essential governmental functions, the authority may not be required to pay any taxes or assessment on any property acquired or used by it for the purposes provided in this chapter; except that service facilities leased or rented by the authority to business entities are subject to taxation and assessments must be made against the tenant in possession based upon the value of the leasehold interest, both real and personal. The authority may not be required to pay any tax upon its income except as may be required by the laws of the United States.