SECTION 1. Section 51 of Chapter 59 of the General Laws is hereby amended by adding the following at the end thereof:

With respect to each parcel of real property classified as class three, commercial, or class four, industrial, in each city or town certified by the Commissioner to be assessing all property at its full and fair cash valuation, and at the option of the Board of Selectmen or Mayor, with the approval of the City Council, as the case may be, by vote of July first of each fiscal year, there shall be an exemption equal to not more than twenty percent of the value of each parcel; provided, however, only the assessed owner or the subsequent owner applies by August first following the acceptance by each city or town in each fiscal year, that such exemption shall apply to property that is occupied by business that, at that location and all other combined, have an average annual employment of no more than ten people during the previous calendar year as certified by the Commissioner of the Department of Employment and Training and the assessed valuation of which is less than $1,000,000.  In properties where all businesses do not qualify, the exemption shall be prorated according to the percentage of square footage of the building that does qualify.  The exemption granted under this provision shall be prorated with the owner of the real estate receiving fifty percent of the benefit and the remaining fifty percent being prorated to the owners of the business that qualify by the owners of the real estate unless lease agreements provide otherwise.  This exemption shall be in addition to any exemption allowable under Section five.  The value of exemptions granted under this Section shall be borne by the combined value of class three, commercial property and class four, industrial property.