19 C.F.R. § 148.53
(a) Exemption. Professional books, implements, instruments, or tools of trade, occupation or employment, may be allowed entry free of duty and tax under the provisions of subheading 9804.00.15, Harmonized Tariff Schedule of the United States (19 U.S.C. 1202), for such articles owned and used abroad by any person emigrating to the United States, or subheading 9804.00.10 for such articles taken abroad by or for the account of any person arriving in the United States. The exemption for emigrants under subheading 9804.00.15, HTSUS shall not be applied to:
[T.D. 73-27, 38 FR 2449, Jan. 26, 1973, as amended by T.D. 89-1, 53 FR 51265, Dec. 21, 1988; CBP Dec. 15-14, 80 FR 61291, Oct. 13, 2015]