Mass. Gen. Laws ch. 79 § 12
The damages for property taken under this chapter shall be fixed at the value thereof before the recording of the order of taking, and in case only part of a parcel of land is taken there shall be included damages for all injury to the part not taken caused by the taking or by the public improvement for which the taking is made; and there shall be deducted the benefit accruing to the part not taken unless it was stated in the order of taking that betterments were to be assessed. In determining the damages to a parcel of land injured when no part of it has been taken, regard shall be had only to such injury as is special and peculiar to such parcel, and there shall be deducted the benefit accruing to such parcel, unless it was stated in the order of taking, or if there was no taking in the order for the establishment, construction, alteration, repair or discontinuance of the public improvement which caused the injury, that betterments were to be assessed. Whenever the title or interest taken is such that the property will be exempt from taxation so long as it is held and used for the purpose for which it is taken, the damages for the taking shall include an amount or amounts separately determined and stated which shall be estimated to be equal to that portion of the tax assessed upon the property for the fiscal year in which it is taken which, if the tax were apportioned pro rata according to the number of days in such fiscal year, would be allocable to the days ensuing after the taking, and an additional amount equal to the tax assessed against the property for the ensuing fiscal year, if the taking is made between January first and June thirtieth inclusive. Notwithstanding the other provisions of this section, in a program eligible for federal financial assistance, whenever the federal government authorizes a federal agency to allow a measure of damage, or other standard for payments to owners of property taken which would increase the payments to said owners over the measure of damages set forth hereunder, then in such cases the measure of damages shall be the measure of damages set forth hereunder plus any such increase, provided that the taking agency will receive partial or full reimbursement from the federal government for such increase.
Mass. Gen. Laws ch. 79, § 12