27 C.F.R. § 70.147 – Priority of interest and expenses.

(a) In general. If the lien imposed by 26 U.S.C. 6321 is not valid as against another lien or security interest, the priority of the other lien or security interest also extends to each of the following items to the extent that under local law the item has the same priority as the lien or security interest to which it relates:
1. (1) Any interest or carrying charges (including finance, service, and similar charges) upon the obligation secured,
2. (2) The reasonable charges and expenses of an indenture trustee (including, for example, the trustee under a deed of trust) or agent holding the security interest for the benefit of the holder of the security interest,
3. (3) The reasonable expenses, including reasonable compensation for attorneys, actually incurred in collecting or enforcing the obligation secured,
4. (4) The reasonable costs of insuring, preserving, or repairing the property to which the lien or security interest relates,
5. (5) The reasonable costs of insuring payment of the obligation secured (including amounts paid by the holder of the security interest for mortgage insurance, such as that issued by the Federal Housing Administration), and
6. (6) Amounts paid to satisfy any lien on the property to which the lien or security interest relates, but only if the lien so satisfied is entitled to priority over the lien imposed by 26 U.S.C. 6321.
(b) Collection expenses. The reasonable expenses described in paragraph (a)(3) of this section include expenditures incurred by the protected holder of the lien or security interest to establish the priority of the holder's interest or to collect, by foreclosure or otherwise, the amount due the holder from the property subject to the protected holder's lien. Accordingly, the amount of the encumbrance which is protected is increased by the amounts so expended by the holder of the security interest.
(c) Costs of insuring, preserving, etc. The reasonable costs of insuring, preserving, or repairing described in paragraph (a)(4) of this section include expenditures by the holder of a security interest for fire and casualty insurance on the property subject to the security interest and amounts paid by the holder of the lien or security interest to repair the property. Such reasonable costs also include the amounts paid by the holder of the lien or security interest in a leasehold to the lessor of the leasehold to preserve the leasehold subject to the lien or security interest. Accordingly, the amount of the lien or security interest which is protected is increased by the amounts so expended by the holder of the lien or security interest.
(d) Satisfaction of liens. The amounts described in paragraph (a)(6) of this section include expenditures incurred by the protected holder of a lien or security interest to discharge a statutory lien for State sales taxes on the property subject to the lien or security interest if both the lien or security interest and the sales tax lien have priority over a Federal tax lien. Accordingly, the amount of the lien or security interest is increased by the amounts so expended by the holder of the lien or security interest even though under local law the holder of the lien or security interest is not subrogated to the rights of the holder of the State sales tax lien. However, if the holder of the lien or security interest is subrogated, within the meaning of § 70.144(b) of this part, to the rights of the holder of the sales tax lien, the holder of the lien or security interest will also be entitled to any additional protection afforded by 26 U.S.C. 6323(i)(2)
(26 U.S.C. 6323).