Section 74. Whenever an abatement is finally made to any corporation taxable under chapter sixty-three upon any tax assessed by the assessors of any town, upon or in respect of works, structures, real estate, motor vehicles, trailers, machinery, poles, underground conduits, wires and pipes, the assessors, commissioners, appellate tax board or court granting such abatement shall forthwith notify the commissioner thereof, and shall state in such notice what sum was determined by such assessors, commissioners, appellate tax board or court to have been the full and fair cash value of such works, structures, real estate, machinery, poles, underground conduits, wires and pipes on the first day of January on which the tax so abated was originally assessed or to have been the proper value of any such motor vehicle or trailer owned by such corporation and assessed under chapter sixty A.