No employer shall cease to be subject to this chapter except upon a finding by the commissioner, after having made such investigation as he may deem necessary, that such employer has not on any day after the first day of the then last completed calendar year employed one or more individuals in employment subject to this chapter, whereupon such employer shall cease to be subject hereto as of January first of the year in which such finding is made.
Mass. Gen. Laws ch. 151A, § 11