Chapter 39 covers plastics and articles thereof, including polymers in primary forms, waste and scrap, and semi-manufactures. This chapter is divided by polymer origin into natural polymers (3913) and synthetic polymers (3901-3912), and includes specialty products such as ion exchangers and adhesives. Primary forms refer to unprocessed forms such as liquid, paste, block, and powder, which are the basic raw materials of the plastics industry. Heading 3913 covers natural polymers not elsewhere specified or included (such as alginic acid, chitin, chitosan, lignin, etc.) and their derivatives, as well as modified natural polymers (such as hardened proteins and chemically modified natural rubber). It does not include regenerated cellulose (3912) or natural rubber (4001). First 2 digits 39: Chapter 39, Plastics and articles thereof. Digits 3-4, 13: Heading 3913, natural polymers not elsewhere specified or included. Digits 5-6, 90: Subheading 391390, other natural polymers in primary forms, i.e., all natural polymers under heading 3913 except 391310 (alginic acid). Code 391390 is a 6-digit subheading, which may be further subdivided to 8-10 digits by national customs authorities. The goods are natural polymers in primary forms, not classified under 3911 (petroleum resins, etc.) or 3912 (cellulose and its derivatives), and are not synthetic polymers, so they are classified under 3913. If they were alginic acid, they would be classified under 391310; other natural polymers such as chitin, chitosan, and lignin are all classified under 391390.
Chapter
Chapter 39 covers plastics and articles thereof, including polymers in primary forms, waste and scrap, and semi-manufactures. This chapter is divided by polymer origin into natural polymers (3913) and synthetic polymers (3901-3912), and includes specialty products such as ion exchangers and adhesives. Primary forms refer to unprocessed forms such as liquid, paste, block, and powder, which are the basic raw materials of the plastics industry.
Heading
Heading 3913 covers natural polymers not elsewhere specified or included (such as alginic acid, chitin, chitosan, lignin, etc.) and their derivatives, as well as modified natural polymers (such as hardened proteins and chemically modified natural rubber). It does not include regenerated cellulose (3912) or natural rubber (4001).
Digit Breakdown
First 2 digits 39: Chapter 39, Plastics and articles thereof. Digits 3-4, 13: Heading 3913, natural polymers not elsewhere specified or included. Digits 5-6, 90: Subheading 391390, other natural polymers in primary forms, i.e., all natural polymers under heading 3913 except 391310 (alginic acid). Code 391390 is a 6-digit subheading, which may be further subdivided to 8-10 digits by national customs authorities.
Classification Basis
The goods are natural polymers in primary forms, not classified under 3911 (petroleum resins, etc.) or 3912 (cellulose and its derivatives), and are not synthetic polymers, so they are classified under 3913. If they were alginic acid, they would be classified under 391310; other natural polymers such as chitin, chitosan, and lignin are all classified under 391390.
📝 Declaration Elements
Product Name: The specific name of the declared goods, such as chitin, chitosan, lignin, etc., which must correspond to the HS code. Source: Indicate the source of the natural polymer, such as shrimp and crab shells, plant fibers, wood, etc. Primary Form: Describe the form, such as powder, granules, blocks, paste, etc., which must meet the definition of primary forms. Composition and Content: Main components and content, such as chitin content ≥90%, moisture, etc. Brand: If there is a brand, declare the brand name; if no brand, declare "none". Model: Product model or specifications, such as viscosity, molecular weight, etc. Packaging Specifications: Packaging method and net weight, such as 25kg/bag. Use: Main use, such as food additive, pharmaceutical excipient, water treatment, etc. Product Name: Chitosan; Source: Extracted from shrimp and crab shells; Primary Form: Powder; Composition and Content: Chitosan ≥95%, moisture ≤10%; Brand: None; Model: Food grade, viscosity 200cps; Packaging Specifications: 25kg/bag; Use: Food additive. Incorrectly classifying modified natural polymers under 3912 (cellulose derivatives). Failing to distinguish alginic acid (391310) from other natural polymers (391390). Confusing natural polymers with synthetic polymers and incorrectly classifying under 3901-3911.
Product Name
The specific name of the declared goods, such as chitin, chitosan, lignin, etc., which must correspond to the HS code.
⚠️ Declaring generically as "natural polymers" without specifying the particular variety.
Source
Indicate the source of the natural polymer, such as shrimp and crab shells, plant fibers, wood, etc.
⚠️ Failing to provide source information, resulting in uncertain classification.
Primary Form
Describe the form, such as powder, granules, blocks, paste, etc., which must meet the definition of primary forms.
⚠️ Declaring finished products or semi-finished products as primary forms.
Composition and Content
Main components and content, such as chitin content ≥90%, moisture, etc.
⚠️ Failing to indicate content, or content not matching actual testing results.
Brand
If there is a brand, declare the brand name; if no brand, declare "none".
⚠️ Omitting brand information or incorrectly declaring it.
Model
Product model or specifications, such as viscosity, molecular weight, etc.
⚠️ Failing to provide the model, making it impossible to distinguish.
Packaging Specifications
Packaging method and net weight, such as 25kg/bag.
⚠️ Incomplete packaging specifications.
Use
Main use, such as food additive, pharmaceutical excipient, water treatment, etc.
Incorrectly classifying modified natural polymers under 3912 (cellulose derivatives).
Failing to distinguish alginic acid (391310) from other natural polymers (391390).
Confusing natural polymers with synthetic polymers and incorrectly classifying under 3901-3911.
🎯 Classification Logic
Core basis for classification: 1) The goods are natural polymers, not synthetic; 2) They are in primary forms; 3) They are not classified under other headings (such as 3911 petroleum resins, 3912 cellulose). If they are alginic acid, classify under 391310; others such as chitin, chitosan, and lignin are classified under 391390. Modified natural polymers, if not named under other headings, are also classified under 3913. 391310 Alginic acid and its salts and esters: Alginic acid is a specific natural polymer listed separately; other natural polymers are classified under 391390. 3912 Cellulose and its chemical derivatives: Cellulose and its derivatives are classified under 3912, even if of natural origin; other natural polymers are classified under 3913. 3901 Polymers of ethylene in primary forms: Synthetic polymers are classified under 3901-3911; natural polymers are classified under 3913. 1302 Vegetable saps and extracts: Natural polymers, if they are plant extracts but not purified, may be classified under 1302; if they are isolated polymers, they are classified under 3913. 3501 Casein, gelatin, etc.: Protein-based polymers, if unmodified, are classified under 3501; modified natural polymers are classified under 3913. Is it a natural polymer? Is it in primary form? Are alginic acid and cellulose excluded? Is it not a synthetic polymer? Is it not classified under other headings?
Basis
Core basis for classification: 1) The goods are natural polymers, not synthetic; 2) They are in primary forms; 3) They are not classified under other headings (such as 3911 petroleum resins, 3912 cellulose). If they are alginic acid, classify under 391310; others such as chitin, chitosan, and lignin are classified under 391390. Modified natural polymers, if not named under other headings, are also classified under 3913.
Confused Codes：
391310 - Alginic acid and its salts and esters
Alginic acid is a specific natural polymer listed separately; other natural polymers are classified under 391390.
3912 - Cellulose and its chemical derivatives
Cellulose and its derivatives are classified under 3912, even if of natural origin; other natural polymers are classified under 3913.
3901 - Polymers of ethylene in primary forms
Synthetic polymers are classified under 3901-3911; natural polymers are classified under 3913.
1302 - Vegetable saps and extracts
Natural polymers, if they are plant extracts but not purified, may be classified under 1302; if they are isolated polymers, they are classified under 3913.
3501 - Casein, gelatin, etc.
Protein-based polymers, if unmodified, are classified under 3501; modified natural polymers are classified under 3913.
Self-Check：
✓ Is it a natural polymer?
✓ Is it in primary form?
✓ Are alginic acid and cellulose excluded?
✓ Is it not a synthetic polymer?
✓ Is it not classified under other headings?
❓ FAQ
How to determine whether a natural polymer belongs to 391390? First confirm that the goods are polymers of natural origin, such as chitin, chitosan, lignin, etc.; second, they must be in primary forms; finally, exclude alginic acid (391310) and cellulose (3912). If these criteria are met, classify under 391390. How are modified natural polymers classified? If after modification they still qualify as natural polymers and are not named under other headings, they are classified under 3913. For example, chemically modified starch is classified under 3505, but other modified natural polymers such as hardened proteins are classified under 3913. What are the HS codes for chitosan and chitin? Both chitosan and chitin belong to other natural polymers and are classified under 391390. However, note that if they are further processed into articles, they may be classified under other chapters. What is the difference in classification between natural polymers and synthetic polymers? Synthetic polymers are classified under 3901-3911, while natural polymers are classified under 3913. For example, polyethylene is classified under 3901, while chitin is classified under 3913. What are common errors in the declaration elements for 391390? Common errors include: failing to declare the specific product name, failing to indicate the source, declaring non-primary forms as primary forms, inaccurate composition and content, etc. How to check the tax rate for 391390? The tax rate must be checked according to the latest customs tariff schedule, which can be found on the website of the General Administration of Customs or by consulting a customs broker. Different rules of origin may apply different agreement rates. Which code should lignin be classified under? If lignin is a natural polymer in primary form, it is classified under 391390. However, if it is lignosulfonate, it may be classified under 3804 or 3806. What is the difference in classification between alginic acid and alginates? Alginic acid and its salts and esters are classified under 391310, while other natural polymers such as chitin are classified under 391390. Note that alginates belong to 391310.
Q: How to determine whether a natural polymer belongs to 391390?
A: First confirm that the goods are polymers of natural origin, such as chitin, chitosan, lignin, etc.; second, they must be in primary forms; finally, exclude alginic acid (391310) and cellulose (3912). If these criteria are met, classify under 391390.
Q: How are modified natural polymers classified?
A: If after modification they still qualify as natural polymers and are not named under other headings, they are classified under 3913. For example, chemically modified starch is classified under 3505, but other modified natural polymers such as hardened proteins are classified under 3913.
Q: What are the HS codes for chitosan and chitin?
A: Both chitosan and chitin belong to other natural polymers and are classified under 391390. However, note that if they are further processed into articles, they may be classified under other chapters.
Q: What is the difference in classification between natural polymers and synthetic polymers?
A: Synthetic polymers are classified under 3901-3911, while natural polymers are classified under 3913. For example, polyethylene is classified under 3901, while chitin is classified under 3913.
Q: What are common errors in the declaration elements for 391390?
A: Common errors include: failing to declare the specific product name, failing to indicate the source, declaring non-primary forms as primary forms, inaccurate composition and content, etc.
Q: How to check the tax rate for 391390?
A: The tax rate must be checked according to the latest customs tariff schedule, which can be found on the website of the General Administration of Customs or by consulting a customs broker. Different rules of origin may apply different agreement rates.
Q: Which code should lignin be classified under?
A: If lignin is a natural polymer in primary form, it is classified under 391390. However, if it is lignosulfonate, it may be classified under 3804 or 3806.
Q: What is the difference in classification between alginic acid and alginates?
A: Alginic acid and its salts and esters are classified under 391310, while other natural polymers such as chitin are classified under 391390. Note that alginates belong to 391310.
⚠️ Disclaimer: HS code classification, declaration elements, tariff rates and regulatory conditions on this page are for reference only and do not constitute legal advice on customs classification. Tariff rates and regulations are subject to change; the latest announcements from the General Administration of Customs and on-site determinations shall prevail. Please consult professional customs brokers or customs authorities before import/export.