Heading 3803 covers tall oil whether crude or refined as a whole product. However, separated fractions — such as tall oil fatty acids or tall oil rosin isolated by distillation — are generally classified under their respective chemical headings rather than under 3803, because they are no longer 'tall oil' as such but distinct chemical products. Importers should confirm the degree of fractionation and the resulting chemical identity before selecting the heading.

Tall oil used as a biofuel feedstock has been the subject of trade disputes in other jurisdictions, and its classification as a renewable feedstock can affect eligibility for certain domestic incentive programs. For US import purposes, the tariff classification under heading 3803 is based on the product's chemical identity as tall oil, not its intended end use. Importers planning to use tall oil in biofuel production should consult with counsel on any applicable domestic program requirements separately from the customs entry.