For purposes of local real estate taxation in the town of Acton under chapter 59 of the General Laws, real property shall be classified as “class one A, senior primary residence”  if it meets the requirements of “class one, residential” property under subsection (b) of section 2A of chapter 59 of the General Laws and (a) the property is owned and occupied by an individual taxpayer or owned and occupied jointly by married taxpayers as the principal residence and domicile of the taxpayer(s) for income tax purposes; (b) the individual taxpayer or one or both of the married taxpayers is a recipient of Social Security retirement benefits or a government pension; (c) those benefits  represent at least 75 per cent of the total income derived by the individual taxpayer or married taxpayers from all sources; and (d) the value of the total assets held by the individual taxpayer or by the married taxpayers are limited to $150,000, not including the value of the primary residence.

SECTION 2.   Notwithstanding chapters 59 and 60 of the General Laws or any other general or special law to the contrary, the board of selectmen of the town of Acton may establish a program to allow an annual exemption from local property tax on a class one A, senior primary residence, equal to the difference between the full amount of property tax due and an amount of tax equal to the previous year’s tax bill indexed by the rate of increase granted by the Social Security Administration, the “senior adjusted  tax”, but the sum of all exclusions granted by the town under this section for any tax year shall not exceed 25 per cent of the assessed value of all class one, residential, parcels within the town.  This exemption shall be in addition to any exemptions allowable under section 5 of chapter 59 of the General Laws, but in no instance shall the taxable valuation of the property after all applicable exemptions be reduced below 50 per cent of its full and fair cash valuation, except through the applicability of section 8A of chapter 58 and of clause eighteenth of section 5 of chapter 59. Where, under section 5 of chapter 59, the exemption is based upon an amount of tax rather than on valuation, the reduction of taxable valuation for purposes of the preceding sentence shall be computed by dividing the amount of tax by the residential class tax rate of the town and multiplying the result by $1000.  Under this program, the total amount of the exemptions granted may be shifted by the board of selectmen during the annual classification hearing to any single class or multiple classes of property, within the town, but the percentage of tax levy imposed on any single class of property shall not exceed 1.75 times the amount imposed under full and fair cash valuation of all taxable property.  For purposes of this paragraph, ""parcel'' shall mean a unit of real property as defined by the assessors in accordance with the deed for the property and shall include a condominium unit, and ownership shall be defined by the deed for the property.

SECTION 3.   This act shall take effect upon its passage.