Chapter 465 of the acts of 1956 is hereby amended by striking out the first paragraph of section 17 and inserting in place thereof the following paragraph:-

The exercise of the powers granted by this act will be in all respects for the benefit of the people of the commonwealth, for the increase of their commerce and prosperity, and for the improvement of their health and living conditions, and as the operation and maintenance of the projects by the authority will constitute the performance of essential governmental functions, the authority shall not be required to pay any taxes or assessments upon any project or any property acquired or used by the authority under the provisions of this act or upon the income therefrom, and the bonds issued under the provisions of this act, their transfer and the income therefrom (including any profit made on the sale therefrom) shall at all times be free from taxation within the commonwealth.  However, real property of the authority, if leased, used, or occupied in connection with a business conducted for profit, shall, for the privilege of such lease, use or occupancy, be valued, classified, assessed and taxed annually as of January 1 to the lessee, user, or occupant in the same manner and to the same extent as if such lessee, user, or occupant were the owner thereof in full. No tax assessed under this section shall be a lien upon the real estate with respect to which it is assessed; nor shall any tax be enforced by any sale or taking of such real estate; but the interest of any lessee therein may be sold or taken by the collector of the town in which the real estate lies for the nonpayment of such taxes in the manner provided by law for the sale or taking of real estate for nonpayment of annual taxes. Notwithstanding the previous sentence, such collector may utilize all other remedies provided by chapter 60 of the general laws for the collection of annual taxes upon real estate and for the collection of taxes assessed under this section.  The Authority is hereby authorized and empowered to enter into an agreement or agreements with the Boston Redevelopment Authority, with the approval of the mayor of the city, where the Authority will undertake to make the city annual payments in lieu of taxes in connection with any real property acquired and owned by the Authority as a part of the trade and transportation center, the amounts of such payments to be reasonable sums stipulated in such agreement or agreements or determined in accordance with a reasonable formula so stipulated.  No such property shall be taxed to a lessee thereof from the Authority regardless of the date of acquisition of such property by the Authority.  No revenue bonds of the Authority shall be issued pursuant to section four B of this act until the Authority shall have entered into such agreement or agreements with the Boston Redevelopment Authority, which agreement or agreements shall be conclusively deemed to comply with the provisions hereof if executed by the Boston Redevelopment Authority and the mayor of the city of Boston.