For purposes of this subparagraph, a contract right (as defined in paragraph (c)(2)(i) of § 301.6323(c)-1 ) is in existence when the contract is made. An account receivable (as defined in paragraph (c)(2)(ii) of § 301.6323(c)-1 ) is in existence when, and to the extent, a right to payment is earned by performance.
A security interest must be in existence, within the meaning of this paragraph, at the time as of which its priority against a tax lien is determined. For example, to be afforded priority under the provisions of paragraph (a) of § 301.6323(a)-1 a security interest must be in existence within the meaning of this paragraph before a notice of lien is filed.
For purposes of this subdivision, the dates described in (A) and (B) of this subdivision (i) shall be determined without regard to any rule or principle of local law which permits the relation back of any requisite action to a date earlier than the date on which the action is actually performed. For purposes of this paragraph, a judgment lien is a lien held by a judgment lien creditor as defined in paragraph (g) of this section.
Example.
Example. On February 1, 1968, A lets a contract for the construction of an office building on property owned by him. On March 1, 1968, in accordance with § 301.6323(f)-1 , a notice of lien for delinquent Federal taxes owed by A is filed. On April 1, 1968, B, a lumber dealer, delivers lumber to A's property. On May 1, 1968, B records a mechanic's lien against the property to secure payment of the price of the lumber. Under local law, B's mechanic's lien is valid against subsequent purchasers of real property without notice from February 1, 1968, which is the date the construction contract was entered into. Because the date on which B's mechanic's lien is valid under local law against subsequent purchasers is February 1, and the date on which B begins to furnish the materials is April 1, the date on which B becomes a mechanic's lienor within the meaning of this paragraph is April 1, the later of these two dates. Under paragraph (a) of § 301.6323(a)-1 , B's mechanic's lien will not have priority over the Federal tax lien, even though under local law the mechanic's lien relates back to the date of the contract.
26 C.F.R. §301.6323(h)-1