Analysis
HTS 2901.24.10 covers buta-1,3-diene and isoprene: buta-1,3-diene under heading 2901 (acyclic hydrocarbons).
Goods classified here enter the United States duty-free at the general (normal trade relations) rate, as do about 26% of the 1050 tariff lines in chapter 29. Free here means free of the base duty only: origin-specific Chapter 99 duties such as Section 301 can still be owed.
The other lines in the same group are 2901.24.20 (having a purity of 95 percent or more by weight, duty-free) and 2901.24.50 (isoprene: other, duty-free).
Census statistics map these goods to NAICS 325110 (Petrochemical Manufacturing), an industry of 76 US establishments employing 10,888 people. That is the industry code a US manufacturer of the same product would normally use.
All 2 neighbouring lines carry the same duty-free rate, so a borderline choice between them changes the statistics reported, not the duty paid.
The general rate of Free has not changed in any edition of the schedule since Jan 2023.
Neighbouring lines
| Line | Description | General rate |
|---|---|---|
| 2901.24.20 | Having a purity of 95 percent or more by weight | Free |
| 2901.24.50 | Isoprene: other | Free |