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SITCSection 5
U.S. imports of heterocyclic compounds with nitrogen hetero-atoms only (nes) (SITC 51577) totaled $185.1M in April 2026, traded with 35 countries.
Importers of Heterocyclic Compounds with Nitrogen Hetero-Atoms Only (NES) paid $5.6M in duties in April 2026 — an effective duty rate of 6.5% on $85.6M in dutiable value, based on actual customs collections rather than the published tariff schedule. Heterocyclic Compounds with Nitrogen Hetero-Atoms Only (NES) imports of $185.1M in April 2026 ran 23% above the year-to-date monthly average of $149.9M.
Last updated: April 2026 dataNitrogen-only heterocyclic compounds not elsewhere specified represent the residual catch-all for ring systems — such as azepines, diazines not covered by pyrimidine headings, and multi-nitrogen scaffolds — that do not fit any of the more specifically enumerated nitrogen-heterocycle subheadings. Because this is a residual category, classification here requires a process of elimination: the compound must be confirmed as not classifiable under pyrazole, imidazole, pyridine, quinoline, pyrimidine, piperazine, triazine, or phenothiazine headings. Many novel pharmaceutical scaffolds and agrochemical candidates land here during early-stage API development.
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The classifier should work through each named nitrogen-heterocycle subheading in order — pyrazole, hydantoin, imidazole, pyridine, quinoline, pyrimidine/piperazine/triazine, and phenothiazine — and confirm the compound's ring system does not match any of them. Only after ruling out all named categories should the compound be placed in the NES subheading. A licensed customs broker with fine-chemical expertise is advisable for novel or complex structures.
Many nitrogen heterocyclic intermediates sourced from China fall within HTS chapters subject to Section 301 tariffs, and the NES category is no exception. Because this is a residual grouping covering diverse structures, the applicable 10-digit HTS code — and its Section 301 status — must be verified for each specific compound before importation.
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Monthly import values over time