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SITCSection 5
U.S. imports of heterocyclic compounds, nes (SITC 51579) totaled $574.2M in July 2026, traded with 49 countries.
Importers of Heterocyclic Compounds, NES paid $13.0M in duties in July 2026 — an effective duty rate of 9.3% on $140.1M in dutiable value, based on actual customs collections rather than the published tariff schedule. Heterocyclic Compounds, NES imports of $574.2M in July 2026 ran 11% below the year-to-date monthly average of $642.4M.
Last updated: July 2026 dataHeterocyclic compounds not elsewhere specified in the SITC schedule encompass ring-system structures containing mixed or unusual heteroatom combinations — such as oxygen-nitrogen or oxygen-sulfur systems — that do not fit any of the more precisely defined subheadings. This residual grouping captures a wide array of advanced intermediates used in agrochemical, pharmaceutical, and materials research, including many proprietary scaffolds at the frontier of drug discovery. Because classification here is by exclusion, importers dealing with novel or multi-heteroatom ring systems should conduct a thorough subheading analysis before filing entry documents.
AI-written summary of the official U.S. Census Bureau trade figures on this page — verify before relying on it.
2.4K shipments/mo
Basic heading 6 of 465 in section 5
Basic heading 51579 · $574.2M of $28.9B
Compounds with mixed heteroatom combinations (e.g., oxazoles containing both O and N, thiadiazoles containing both S and N) and unusual or large ring systems that are not enumerated in any specific subheading are the most frequent occupants of the NES category. Proprietary pharmaceutical scaffolds and novel agrochemical candidates also frequently land here before a more specific classification ruling is obtained.
Yes — because NES classification is inherently a residual determination, CBP binding ruling requests are particularly valuable for heterocyclic compounds in this category. A ruling provides legal certainty on the correct 10-digit HTS code, applicable duty rate, and any trade-remedy exposure, reducing the risk of reclassification and retroactive duty liability.
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Imports · July 2026
origin
Ireland and China together supply 78% of it.
customs district
Census does not publish district detail for this classification system.
destination
Census does not publish state detail for this classification system.
entry
Census does not publish port detail for this classification system.
ImportsExports
Imports
$574.2MYoY · Pro
Exports
$179.6MYoY · Pro
12-mo low · imports
YoY · ProThrough July 2026. Source: U.S. Census Bureau.