HS 400231 Isobutene-isoprene (butyl) rubber (IIR); halo-isobutene-isoprene rubber (CIIR or BIIR)
Quick Answer: Isobutene-isoprene (butyl) rubber (IIR) and halo-isobutene-isoprene rubber (CIIR or BIIR) imported under HS 400231 enters the UK at 0.00%, the EU at 0.00%, and the US at a Free rate for certain types and 20% for others. This classification covers synthetic rubbers derived from isobutene and isoprene, including brominated and chlorinated variants. These materials are primarily used in the manufacturing of tires, inner tubes, seals, and vibration dampeners due to their excellent impermeability to gases and resistance to heat and chemicals. Importers should verify the specific sub-classification and origin to determine the exact duty applicable in the US. CustomTariffs aggregates this data for trade compliance.
What Are the Import Duty Rates?
🇬🇧 United Kingdom
| Code | MFN | Preferential | Unit |
|---|---|---|---|
| 4002310000 | 0.00 % | — | — |
🇪🇺 European Union (TARIC)
| Code | MFN | Preferential | Unit |
|---|---|---|---|
| 4002310000 | 0.00 % | — | — |
🇺🇸 United States (HTSUS)
| Code | MFN | Preferential | Unit |
|---|---|---|---|
| 4002310000 | Free | — | ["kg"] |
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.
How to Classify This HS Code?
What products does HS 400231 cover?
This subheading covers synthetic rubbers of the isobutene-isoprene (butyl) type, commonly known as IIR, and its halogenated forms, specifically halo-isobutene-isoprene rubber (CIIR or BIIR). According to the World Customs Organization's Harmonized System Nomenclature, these are synthetic rubbers produced by polymerization. The US International Trade Commission (USITC) Harmonized Tariff Schedule (HTS) and the EU's TARIC database confirm that this category includes the raw, uncompounded forms of these specific synthetic elastomers, which are vital for manufacturing products requiring excellent impermeability to gases and good resistance to heat and chemicals.
What falls outside HS 400231?
The following products are excluded from HS 400231: synthetic rubbers not falling within the isobutene-isoprene (butyl) or halo-isobutene-isoprene (CIIR/BIIR) categories, such as styrene-butadiene rubber (SBR) or polybutadiene rubber (BR), which are classified under HS 4002. Also excluded are compounded rubbers that have undergone further processing with additives, vulcanizing agents, or fillers, as these are typically classified under HS 4005. Finished or semi-finished articles made from butyl or halo-butyl rubber, such as inner tubes or seals, are also classified in their respective headings, not as raw rubber.
What are common classification mistakes for HS 400231?
A common error is misclassifying compounded butyl rubber or finished articles as raw butyl rubber under HS 400231. This often occurs when importers overlook the distinction between the raw polymer and materials that have been mixed with other substances or formed into specific shapes. According to General Interpretative Rule 1 of the Harmonized System, classification is determined by the terms of the headings and any relative section or chapter notes. If a product is a mixture or compound, it should be classified according to the rules for mixtures and compounds (e.g., HS 4005) unless otherwise specified.
How should importers classify products under HS 400231?
The correct procedure for classifying products under HS 400231 involves a thorough examination of the product's technical specifications and composition. Importers and customs brokers must verify that the material is indeed isobutene-isoprene (butyl) rubber or its halogenated variants (CIIR/BIIR) and that it is in its raw, uncompounded form. Consulting the WCO HS Explanatory Notes, the USITC HTS, or the EU TARIC database for detailed descriptions and exclusions is crucial. Obtaining a detailed technical data sheet from the supplier, confirming the polymer type and absence of significant additives, is a key step.
How is the duty calculated for products under HS 400231?
A shipment of 10,000 kilograms of raw isobutene-isoprene (butyl) rubber, declared at a customs value of $25,000 USD, would attract a US duty of $1,250 USD. This is calculated using the Most Favored Nation (MFN) duty rate of 5.0% ad valorem, applied to the declared customs value ($25,000 USD × 0.05 = $1,250 USD). This rate is published in the USITC Harmonized Tariff Schedule for subheading 4002.31.0000.
Which trade agreements reduce duties for HS 400231?
Several free trade agreements may reduce the applicable duty rate for HS 400231, including the United States-Mexico-Canada Agreement (USMCA). Under USMCA, qualifying butyl rubber originating from Canada or Mexico can enter the United States duty-free. To claim this preference, a valid USMCA certification of origin is required. While not directly applicable to this specific product, the EU's preferential trade agreements with certain countries may offer reduced rates, often requiring an EUR.1 movement certificate for goods originating from those partner nations.
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FAQ
What are the typical import duty rates for HS code 400231 (Isobutene-isoprene rubber)?
The duty rates for HS code 400231, which covers Isobutene-isoprene (butyl) rubber (IIR) and halo-isobutene-isoprene rubber (CIIR or BIIR), vary by country. For example, under the US Harmonized Tariff Schedule (HTS), the Most Favored Nation (MFN) rate is 0.00%. In the European Union, under the TARIC system, the rate is also often 0.00% for many trading partners. The UK Trade Tariff also lists a 0.00% duty rate under its standard import duty. It is crucial to verify the specific rate applicable to your country of import and the origin of the goods, as preferential rates under Free Trade Agreements (FTAs) may apply.
How is the duty for HS code 400231 calculated, and can you provide an example?
The duty for HS code 400231 is typically calculated as an ad valorem rate, meaning it's a percentage of the value of the imported goods. For instance, if the MFN duty rate is 0.00%, the calculation is straightforward: 0.00% of the declared customs value. Let's assume a shipment of butyl rubber valued at $10,000 USD. If the applicable duty rate were 3.5% (hypothetical for illustration, as the actual rate is often 0%), the duty would be calculated as: $10,000 (Value) × 0.035 (Duty Rate) = $350.00 (Duty Amount). Since the actual MFN rate is 0.00%, the duty payable would be $0.00.
What are the key classification criteria to ensure correct use of HS code 400231?
To correctly classify goods under HS code 400231, the primary criterion is the chemical composition and type of synthetic rubber. This code specifically covers 'Isobutene-isoprene (butyl) rubber (IIR)' and its halogenated forms, 'halo-isobutene-isoprene rubber (CIIR or BIIR)'. Importers must ensure that the product is indeed a synthetic rubber falling within these specific chemical structures. Documentation from the manufacturer, such as a Certificate of Analysis or technical data sheet, detailing the polymer type and its properties, is essential to substantiate the classification. This distinguishes it from other synthetic rubbers or natural rubber.
What documentation is typically required for importing goods classified under HS code 400231?
When importing goods under HS code 400231, standard import documentation is generally required. This includes a commercial invoice detailing the value, quantity, and description of the goods; a packing list; and a bill of lading or air waybill. Crucially, to support the HS classification, a manufacturer's declaration or technical data sheet specifying that the material is Isobutene-isoprene (butyl) rubber (IIR) or halo-isobutene-isoprene rubber (CIIR or BIIR) is highly recommended. Depending on the importing country and any specific trade agreements being claimed, a Certificate of Origin may also be necessary.
Do common trade agreements, like USMCA or EU FTAs, offer preferential duty rates for HS code 400231?
Yes, common trade agreements can significantly impact the duty rates for HS code 400231. For example, under the United States-Mexico-Canada Agreement (USMCA), goods that meet the rules of origin may qualify for duty-free entry. Similarly, the European Union has numerous Free Trade Agreements (FTAs) with various countries that often provide for reduced or eliminated tariffs on synthetic rubber products, including those classified under 400231. To benefit from preferential rates, importers must ensure the goods meet the specific rules of origin stipulated in the relevant trade agreement and possess a valid Certificate of Origin or other required proof.