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SITCSection 5
U.S. imports of heterocyclic compounds, nes (SITC 51579) totaled $570.9M in April 2026, traded with 46 countries.
Importers of Heterocyclic Compounds, NES paid $8.6M in duties in April 2026 — an effective duty rate of 7.2% on $119.6M in dutiable value, based on actual customs collections rather than the published tariff schedule.
Last updated: April 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.
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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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| Country | Imports | Exports | Balance |
|---|---|---|---|
| SINGAPORE | $299.6M | $1.3M | -$298.2M |
| BELGIUM | $65.5M | $7.1M | -$58.4M |
| CHINA | $54.8M | $2.1M | -$52.8M |
| SWITZERLAND | $41.7M | $4.0M | -$37.7M |
| INDIA | $35.4M | $2.0M | -$33.4M |
Monthly import values over time