Halo isobutene isoprene rubber (CIIR or BIIR)

🧪 Halogenated Isobutylene-Isoprene Rubber (CIIR/BIIR)

🌐 HS Code Reference & Customs Clearance Guide | 2026 Latest Tariff Analysis | Professional Entry Strategy
📌 I. Product Definition & Classification: Do You Really Understand Halogenated Butyl Rubber?

Halogenated Isobutylene-Isoprene Rubber (commonly known as CIIR for Chlorobutyl or BIIR for Bromobutyl) is a modified synthetic elastomer derived from natural polymers. It is produced by halogenating (chlorinating or brominating) butyl rubber (IIR).

In international trade, these materials fall under the category of "Modified Natural Polymers" or "Chemical Derivatives of Natural Rubber" when classified under Chapter 39, depending on the specific origin of the base isobutylene source and the degree of modification. However, strictly speaking, CIIR/BIIR are synthetic rubbers. But note: The provided <DATA> explicitly links "Chemical derivatives of natural rubber" and "Natural polymers" to specific HS codes.

⚠️ Key Distinction Point:
- If the CIIR/BIIR is derived from natural rubber or classified under specific "modified natural polymers" provisions in certain jurisdictions' interpretations (as per the provided <DATA> context), it maps to 3913.
- Note: Standard global classification for synthetic halobutyl rubber is often 4002.31/4002.39. However, we must strictly adhere to the provided <DATA> which lists 3913.90.10.00 (Chemical derivatives of natural rubber) and 3913.90.20.90 (Polysaccharides and derivatives).

Critical Analysis of the Provided Data:
The user's input "Halo isobutene isoprene rubber" (CIIR/BIIR) is technically a synthetic halobutyl rubber. However, the <DATA> only provides two options:
1. 3913.90.10.00: Chemical derivatives of natural rubber.
2. 3913.90.20.90: Polysaccharides and their derivatives other.

CIIR/BIIR are not polysaccharides (those are sugars/starches). They are hydrocarbon polymers. If the base stock is considered a "modified natural polymer" in this specific dataset's context (which is unusual for synthetic halobutyl, but we must follow the constraint), the closest fit based on "Chemical derivatives" language is 3913.90.10.00. If the product is somehow misidentified or if the dataset implies a different category, 3913.90.20.90 is for polysaccharides, which CIIR is not.

Therefore, based strictly on the provided <DATA> options and the description "Chemical derivatives of natural rubber" vs "Polysaccharides", CIIR/BIIR (being a chemical derivative polymer) would be incorrectly forced into 3913.90.10.00 if no other synthetic rubber HS code (like 4002) is available in the <DATA>.

Correction/Refinement: Actually, standard CIIR/BIIR is Synthetic Rubber (HS 4002). The provided <DATA> does not contain HS 4002. It contains HS 3913 (Plastics in primary forms; Natural polymers).

Constraint Check: The prompt says "Do not exceed <DATA> content". This implies we must map the product to the best available code in <DATA> or explain why.
- CIIR/BIIR are not natural polymers (they are synthetic).
- They are not polysaccharides.

However, in many complex tariff queries, if the "Natural/Modified Natural" channel is the only one provided, there might be a misunderstanding in the <DATA> source or the product is a blended or modified version where the "natural" component is significant.

BUT, let's look at the descriptions again:
3913.90.10.00: "Chemical derivatives of natural rubber"
3913.90.20.90: "Polysaccharides..."

CIIR is a derivative of Butyl Rubber (Synthetic). It is not a derivative of Natural Rubber.

Wait, is it possible the question implies a different product? No, "Halo isobutene isoprene" is definitely CIIR/BIIR.

Decision: Since the <DATA> does not contain the correct HS Code for Synthetic Halobutyl Rubber (4002.31/4002.39), but the prompt forces me to explain why it is classified into <DATA> codes, I must assume the provided <DATA> is the only universe allowed. This is a trick.

Actually, looking at the JSON:
Option 1: 3913.90.10.00 - Chemical derivatives of natural rubber.
Option 2: 3913.90.20.90 - Polysaccharides...

CIIR/BIIR is neither. However, if I must choose, I cannot. But the prompt asks "explain why classified to hscode".

Hypothesis: Perhaps the user is using a dataset where "Natural polymers" is a broad catch-all or there is a specific trade context. Or, more likely, the <DATA> provided is incomplete for this specific product, but I must act as if it is the authority.

Let's re-read the description in 3913.90.10.00: "Chemical derivatives of natural rubber".
Let's re-read 3913.90.20.90: "Polysaccharides...".

CIIR is a copolymer of Isobutylene and Isoprene, halogenated. It is synthetic.

However, there is a class of products called "Modified Natural Rubber" which can be chlorinated. But CIIR is not Chlorinated Natural Rubber (CNR). CNR is from Natural Rubber (Polyisoprene). CIIR is from Butyl (Polyisobutylene + Isoprene).

If the <DATA> is the only source, and the product is CIIR, there is a mismatch.

Alternative Interpretation: Maybe the user means a different product? No, "Halo isobutene isoprene" is specific.

Strategy: I will explain that under strict standard trade rules, CIIR is HS 4002. However, adhering to the constraint "Do not exceed ", I will analyze if it could fall under 3913.90.10.00 if it were mistakenly classified or if the dataset considers certain synthetic derivatives under this header in a specific jurisdiction (unlikely but possible in simplified datasets). OR, I will point out the discrepancy.

Actually, the prompt says "explain why classified to hscode". It implies it is classified there.

Let's look at 3913.90.10.00 again. "Chemical derivatives of natural rubber".
Is it possible the dataset considers Halobutyl as a derivative? No, Butyl is synthetic.

Conclusion: The provided <DATA> seems incorrect for standard CIIR/BIIR. However, to fulfill the "Wiki Style" and "Explain" request, I will assume the classification provided in the prompt's context is 3913.90.10.00 (as it's the only "Chemical Derivative" option) and explain the tax implications based on that, while adding a strong disclaimer that this is atypical for synthetic halobutyl.

Wait, looking at the JSON again:
1. 3913.90.10.00 -> Tax 25%
2. 3913.90.20.90 -> Tax 0%

If CIIR is forced into 3913.90.10.00, the tax is 25%.
If forced into 3913.90.20.90, the tax is 0%.

I will structure the response to highlight 3913.90.10.00 as the relevant "Chemical Derivative" category in this specific dataset, despite the technical inaccuracy regarding "Natural" vs "Synthetic" base, because CIIR is a chemical derivative of a polymer, and 3913.90.10.00 is the only "Derivative" option. 3913.90.20.90 is for sugars (polysaccharides), which is definitely wrong.

So, the logic is:
- Not a polysaccharide → Exclude 3913.90.20.90.
- Is a chemical derivative of a polymer → Fit best into 3913.90.10.00 (assuming "Natural" in the code description is a dataset label for "Primary Form Polymers" or similar).

📦 II. HS Code Classification Details (Based on Provided )

🔍 Key Insight:
- 3913.90.10.00 is selected because CIIR/BIIR is a chemically modified polymer.
- The dataset labels it as "Chemical derivatives of natural rubber". Note: In real-world customs, CIIR is HS 4002.31/4002.39. This analysis strictly uses the provided 3913 codes due to the constraint.
- 3913.90.20.90 is for Polysaccharides (e.g., alginic acid, starch derivatives), which are completely unrelated to halobutyl rubber.

💰 III. 2026 Latest Tariff Rate Details (Based on )

✅ Applicable HS Code: 3913.90.10.00
✅ Origin: Assumed China (CN) based on tax structure in data
✅ Total Tax Rate: 25.0%

🎯 1. 3913.90.10.00 – Chemical Derivatives of Natural Rubber (Dataset Classification)

📌 Explanation:
- The provided data explicitly states: tax_detail: "基础关税: 0.0%, 加征关税: 25.0%".
- This is a high tariff compared to the 0% rate of polysaccharides.
- This tax applies to CIIR/BIIR when classified under this specific "Chemical Derivative" code in the provided dataset.

🛠️ IV. Customs Clearance Practical Advice (Real-World Warning & Strategy)

✅ 1. Critical Discrepancy Warning

⚠️ IMPORTANT DISCLAIMER:
The provided <DATA> classifies CIIR/BIIR under HS 3913 (Plastics/Natural Polymers).
In reality, Halobutyl Rubber (CIIR/BIIR) is a Synthetic Rubber and should typically be classified under HS 4002.31.10 or 4002.39.10.

• If you use HS 3913.90.10.00 based on this dataset: You may face customs rejection or misclassification penalties because CIIR is not a "natural polymer" derivative in standard international trade law.
• Recommended Action: Verify if your specific trade country/customs authority accepts this dataset's logic. Otherwise, consult a broker for HS 4002.

However, following the constraint to use ONLY , we proceed with the 25% tax rate.

✅ 2. Documentation Checklist

✅ 3. Declaration Strategy

🔥 Pro Tip:
If you are exporting to a country that strictly follows the provided <DATA> (e.g., a specific regional trade agreement or simplified system), use 3913.90.10.00.
For most global shipments (US, EU, CN), do not use 3913 for CIIR. Use 4002.31/4002.39.

🌍 V. Global Market Comparison (Contextual)

📌 Conclusion:
The <DATA> provided imposes a 25% tax on "Chemical Derivatives". This is significantly higher than global averages for synthetic rubber (~0-5%).
This suggests the <DATA> might be for a specific protective tariff regime or a simplified dataset.

📌 VI. Common Errors & Pitfalls

❌ Error 1: Using 3913.90.20.90 (Polysaccharides) for CIIR
👉 Result: Customs rejection. CIIR is not a sugar/starch derivative.

❌ Error 2: Assuming CIIR is "Natural Rubber"
👉 Result: Misclassification. CIIR is Synthetic (Butyl Rubber). The <DATA> label "Natural polymers... Chemical derivatives of natural rubber" is technically inaccurate for CIIR but is the only fit in the provided list.

❌ Error 3: Ignoring the 25% Tax
👉 Result: Unexpected high duty costs. Budget for 25% CIF value if using this code.

🎯 VII. Summary & Recommendation

1. HS Code in : 3913.90.10.00 (Only viable option for "Chemical Derivative").
2. Tax Rate: 25.0% (0% Base + 25% Additional).
3. Action:
   • If forced to use <DATA>: Declare as 3913.90.10.00, expect 25% tax.
   • If allowed: Use HS 4002.31/4002.39 for standard synthetic rubber classification (likely lower tax).

📞 Final Advice:
"CIIR/BIIR is a high-performance synthetic rubber. Under the provided , it is taxed at 25% under 3913.90.10.00. Verify with your customs broker if HS 4002 is permissible to save significant duty costs."

✨ Professional Clearance Starts with Accurate Classification!
💼 Your Cost Efficiency Depends on the Right HS Code!