HS 391000 Liquid poly(methylhydrosiloxane) with terminal trimethylsilyl groups (CAS RN 63148-57-2) with a purity by weight of 99,9 % or more
Quick Answer: Liquid poly(methylhydrosiloxane) with terminal trimethylsilyl groups (CAS RN 63148-57-2) with a purity of 99.9% or more imported under HS 391000 enters the UK at 6.00%, the EU at 6.50%, and the US at 3% under the MFN rate, with duty-free entry from several preferential trade partners. This classification specifically covers a high-purity silicone fluid used in various industrial applications, including as a release agent, lubricant, and intermediate in chemical synthesis. Importers should be aware of potential variations in duty rates based on country of origin, particularly for the US market. CustomTariffs aggregates this information to assist with compliance.
What Are the Import Duty Rates?
🇬🇧 United Kingdom
| Code | MFN | Preferential | Unit |
|---|---|---|---|
| 3910000010 | 6.00 % | — | — |
| 3910000020 | 6.00 % | — | — |
| 3910000035 | 6.00 % | — | — |
| 3910000045 | 6.00 % | — | — |
| 3910000055 | 6.00 % | — | — |
🇪🇺 European Union (TARIC)
| Code | MFN | Preferential | Unit |
|---|---|---|---|
| 3910000035 | 6.50 % | — | — |
| 3910000040 | 6.50 % | — | — |
| 3910000045 | 6.50 % | — | — |
| 3910000050 | 6.50 % | — | — |
| 3910000010 | 6.50 % | — | — |
🇺🇸 United States (HTSUS)
| Code | MFN | Preferential | Unit |
|---|---|---|---|
| 3910000000 | 3% | Free (18 programs) | ["kg"] |
Special rates available under trade agreements including USMCA, KORUS, GSP.
Duty rates sourced from the USITC (US International Trade Commission) Harmonized Tariff Schedule (HTS) (accessed 2/22/2026), EU TARIC – DG TAXUD (Directorate-General for Taxation and Customs Union) (accessed 2/22/2026), and UK Trade Tariff – HMRC (His Majesty's Revenue and Customs) (accessed 2/22/2026).
Data compiled and presented by HSRates.
Which Trade Agreements Reduce Duties for HS 3910.00?
Imports of Liquid poly(methylhydrosiloxane) with terminal trimethylsilyl groups (CAS RN 63148-57-2) with a purity by weight of 99,9 % or more may qualify for reduced or zero duty rates under free trade agreements and preferential programs. The overview below shows available preferential arrangements by jurisdiction, compiled by HSRates from official tariff and trade agreement data.
United States (HTSUS)
Free for USMCA, KORUS, and 16 other programs
European Union (TARIC)
Preferential rate data not yet available.
United Kingdom
Preferential rate data not yet available.
Preferential rates require proof of origin and may be subject to quotas or conditions. Always verify eligibility with a licensed customs broker.
Data compiled by HSRates.
Which Preferential Rates Apply to Your Origin Country?
Select an origin country to see if preferential rates apply.
Preferential rates based on available trade agreements. Actual rates may vary.
How to Classify This HS Code?
What products does HS 391000 cover?
This subheading covers liquid poly(methylhydrosiloxane) with terminal trimethylsilyl groups, specifically identified by CAS RN 63148-57-2, when its purity by weight is 99.9% or greater. According to the World Customs Organization (WCO) Harmonized System Nomenclature, this specific silicone polymer falls under Heading 3910, which pertains to silicones in primary forms. The USITC Harmonized Tariff Schedule (HTS) and the EU's TARIC database confirm this precise chemical specification for classification within this subheading.
What falls outside HS 391000?
The following products are excluded from HS 391000: poly(methylhydrosiloxane) with a purity below 99.9% by weight, other types of silicones not meeting the specific chemical structure (e.g., polydimethylsiloxane), or silicones that are not in liquid form. For instance, solid silicone resins or silicone fluids with different terminal groups would be classified elsewhere, potentially under other subheadings within Chapter 39 or other chapters depending on their specific properties and uses.
What are common classification mistakes for HS 391000?
A common error is misinterpreting the purity requirement; any poly(methylhydrosiloxane) with terminal trimethylsilyl groups with a purity less than 99.9% by weight will not qualify for this subheading. Another mistake involves classifying other silicone compounds or mixtures that do not precisely match the chemical description and purity criteria. Adherence to General Rule of Interpretation (GRI) 1, which states that classification shall be determined according to the terms of the headings and any relative section or chapter notes, is crucial.
How should importers classify products under HS 391000?
The correct procedure for classifying products under HS 391000 involves obtaining a detailed technical specification sheet from the manufacturer that clearly states the chemical name, CAS RN (63148-57-2), and the purity by weight, confirming it is 99.9% or more. Importers and customs brokers must then cross-reference this information with the official tariff schedule of the importing country, such as the USITC HTS or the EU TARIC, to ensure the product meets all criteria for this specific subheading.
How is the duty calculated for products under HS 391000?
A shipment of "Liquid poly(methylhydrosiloxane) with terminal trimethylsilyl groups (CAS RN 63148-57-2) with a purity by weight of 99.9% or more" weighing 100 kg and declared at a customs value of $5,000 USD would attract a US duty of $175.00. This is calculated using the U.S. Harmonized Tariff Schedule's Most Favored Nation (MFN) rate of 3.5% ad valorem, applied to the declared customs value ($5,000 USD × 0.035 = $175.00).
Which trade agreements reduce duties for HS 391000?
Several free trade agreements may reduce the applicable duty rate for HS 391000, including the United States-Mexico-Canada Agreement (USMCA). Under USMCA, originating goods from Canada and Mexico may receive a duty rate of Free. To claim this preferential rate, a self-certified origin statement on the commercial invoice or a separate certificate of origin is typically required, depending on the specific circumstances and value of the shipment, for goods originating from these countries.
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FAQ
What are the typical import duty rates for HS code 391000, specifically for liquid poly(methylhydrosiloxane) with terminal trimethylsilyl groups (CAS RN 63148-57-2) and 99.9% purity?
The Most Favored Nation (MFN) duty rate for HS code 391000 can vary. For example, the United States applies a 6.50% ad valorem duty. The European Union's TARIC system may show rates such as 3% ad valorem, while the UK Trade Tariff might list a rate of 6.00% ad valorem. It is crucial to consult the specific tariff schedule of the importing country for the definitive rate applicable at the time of import.
How is the import duty for HS code 391000 calculated? Can you provide an example?
Import duty for HS code 391000 is typically calculated on an ad valorem basis, meaning it's a percentage of the declared customs value of the goods. For instance, if importing 100 kg of liquid poly(methylhydrosiloxane) valued at $5,000 USD into the United States, and the MFN duty rate is 6.50%, the duty calculation would be: $5,000 (Customs Value) × 6.50% (Duty Rate) = $325.00 USD in duty. Always confirm the basis of valuation (e.g., CIF - Cost, Insurance, Freight) as per the importing country's regulations.
What are the key classification criteria for HS code 391000 to ensure correct declaration?
To correctly classify goods under HS code 391000, importers and brokers must verify that the product is indeed a 'liquid poly(methylhydrosiloxane) with terminal trimethylsilyl groups (CAS RN 63148-57-2)' and that its purity by weight is '99.9 % or more'. The physical state (liquid) and the specific chemical composition, including the terminal groups and high purity, are critical for distinguishing it from other silicones or polymers. Referencing the product's Safety Data Sheet (SDS) and Certificate of Analysis (CoA) is essential.
Which common trade agreements offer preferential duty rates for HS code 391000, and what documentation is needed?
Many trade agreements can offer reduced or free duty rates for HS code 391000. For example, under certain agreements, countries like Australia (AU), Canada (CA), Chile (CL), South Korea (KR), and Singapore (SG) may benefit from preferential rates, potentially including 'Free' entry. To claim these preferential rates, importers typically need a Certificate of Origin (COO) or a declaration of origin from the exporter, compliant with the specific requirements of the trade agreement in force between the exporting and importing countries. Always verify the specific terms and required documentation for each agreement.
Are there specific documentation requirements beyond a Certificate of Origin for importing liquid poly(methylhydrosiloxane) under HS 391000?
Yes, beyond a Certificate of Origin for preferential trade agreements, importers and customs brokers should be prepared to provide a detailed commercial invoice, a packing list, and a Bill of Lading or Air Waybill. Crucially, for HS code 391000, a Certificate of Analysis (CoA) confirming the chemical identity, purity (99.9% or more), and physical state (liquid) of the poly(methylhydrosiloxane) is often required by customs authorities to substantiate the classification. A Safety Data Sheet (SDS) may also be requested.