18- 125 C.M.R. ch. 303, § 3
Where the sale of tangible personal property is claimed to be non-taxable, the purchaser must provide the seller with a certificate in the form prescribed by the State Tax Assessor; and on the furnishing of such certificate the purchaser shall be held solely accountable for the payment to the State of any taxes, together with penalties and interest thereon, that may later be determined to be due on such purchases in accordance with the applicable provision of the law or this rule.
The certificate is considered a part of each order for the tangible personal property unless the purchaser advises the seller to the contrary at the time the order is placed, and remains in effect until revoked by the purchaser in writing.
18- 125 C.M.R. ch. 303, § 3