Analysis
HTS 3803.00.00 covers tall oil, whether or not refined under heading 3803 (tall oil, whether or not refined).
The normal trade relations rate here is zero, shared by about 25% of the 179 tariff lines in chapter 38, a useful check when a neighbouring dutiable line is a candidate. Free here means free of the base duty only: origin-specific Chapter 99 duties such as Section 301 can still be owed.
It is the only US line under subheading 3803.00, so the six-digit code used by every Harmonized System country and the eight-digit US line describe the same goods; a foreign tariff or an exporter's invoice showing 3803.00 points straight here.
Goods from countries without normal trade relations pay the column 2 rate of 20% instead of nothing, so origin decides between free entry and a 20% duty.
Census statistics map these goods to NAICS 325194 (Cyclic Crude, Intermediate, and Gum and Wood Chemical Manufacturing), an industry of 68 US establishments employing 5,542 people. That concordance is how imports of this line are compared with US output.