verify a 21J COC here:

As a Commonwealth of Massachusetts, Registered Professional Engineering (P.E.) Corporation, UST Inspection Services is uniquely qualified to certify Certificate of Compliance applications in accordance with 503 CMR § 2.07(2)(c) and (d).

Please feel free to contact us for more information:
UST Inspection Services Inc.
781-383-UST3 (8783)

Mass Dept Of Revenue, 21J Certificate of Compliance

10 Ash St.    Cohasset, MA 02025 781-383-UST3 (8783)