Section 5I. With respect to each parcel of real property classified as class three, commercial, 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, there shall be an exemption equal to not more than ten percent of the value of the parcel; provided, however, that such exemption shall only apply to property that is occupied by a business that, at that location and all others combined, had an average annual employment of no more than ten during the previous calendar year as certified by the secretary of labor and workforce development or, where the business is a sole proprietorship or partnership not subject to the provisions of chapter 151A, as determined by the assessors, and the assessed valuation of which is less than one million dollars. This exemption shall be in addition to any exemptions 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.

In those cities and towns in which an exemption is made available hereunder, a taxpayer aggrieved by the failure to receive such commercial exemption may apply for such commercial exemption to the assessors, in writing, on a form approved by the commissioner, on or before the deadline for an application for exemption under section 59.

A timely application filed hereunder shall, for the purposes of this chapter, be treated as a timely filed application pursuant to section 59.