Lithium carbonate falls within the residual carbonates NES heading at the SITC level. At the HTS level it has a more specific provision, and imports from certain origins — particularly China — may be subject to Section 301 tariffs. Given lithium carbonate's strategic importance for battery manufacturing, importers should verify the current tariff treatment and any applicable exclusions with a licensed customs broker before entry.

Because the NES heading covers chemically distinct compounds with different commercial values and potentially different duty rates at the HTS level, the commercial invoice and certificate of analysis should clearly identify the chemical name, CAS number, purity, and form (anhydrous, hydrated, precipitated, ground, etc.). Vague descriptions such as 'carbonate salt' are insufficient and may trigger a customs examination or request for additional information.