Conn. Gen. Stat. § 12-65: Agreements fixing assessments on multifamily housing.

Any municipality acting through its board of selectmen, town council, court of common council or other governing body shall have the power to enter into a written agreement with a taxpayer fixing the assessment of real estate to be used for a housing project consisting of three or more housing units to be constructed or rehabilitated, provided: (a) The real estate to be used for said housing project is in a redevelopment area, community development area or neighborhood strategy area, included (1) in a redevelopment plan approved by a redevelopment agency pursuant to section 8-127, (2) in an urban renewal project authorized by a redevelopment agency pursuant to section 8-141 or (3) in a community development plan approved by the municipality under sections 8-169a to 8-169j, inclusive; (b) the term of such agreement shall not exceed fifteen years from the date of the completion of the housing project or completion of rehabilitation of the housing project or sixteen years from the date of the agreement, whichever is the shorter period; (c) the assessment agreed on for the real estate plus future improvements shall not be less than the assessment as of the last regular assessment date of the real estate without such future improvements. If the municipality claims that the taxpayer is not complying with the terms of such agreement, the municipality may bring an action in the superior court of the judicial district in which the municipality is located to force compliance with such agreement; but a mortgagee may loan its money in reliance on such agreement and nothing herein contained shall be construed to permit the municipality to increase the assessment during the aforesaid period beyond the amount agreed on.