Chapter 39 covers plastics and articles thereof, and is a core chapter in the HS classification organized by material properties. This chapter includes polymers in primary forms (such as resins and pellets), semi-finished products (such as rods, tubes, and profiles), and finished products (such as films, sheets, and containers), but excludes articles mixed with textiles, rubber, etc. Primary forms refer to unprocessed forms such as liquids, pastes, blocks, powders, and granules, which are the basic raw materials of the plastics industry. The notes to this chapter clarify the boundaries with Chapter 28, Chapter 40, etc., and emphasize that polymers must meet chemical definitions and processing conditions. Heading 3903 specifically covers styrene polymers in primary forms, including polystyrene (3903.11-3903.19), styrene-acrylonitrile copolymers (3903.20), styrene-acrylonitrile-butadiene copolymers (ABS, 3903.30), and other styrene copolymers (3903.90). This heading focuses on polymers in which styrene is the principal monomer unit and emphasizes the significant proportion of styrene in the copolymers. Styrene-acrylonitrile copolymer (SAN) usually contains about 70-80% styrene and 20-30% acrylonitrile, and has high transparency, chemical resistance, and rigidity, and is widely used in home appliances, automotive interiors, and packaging. Code 390320 is a six-digit subheading: the first 2 digits "39" represent Chapter 39, "Plastics and articles thereof," defining the broad category; the 3rd-4th digits "03" represent the heading "Styrene polymers in primary forms," identifying styrenic polymers; the 5th-6th digits "20" represent the subheading "Styrene-acrylonitrile copolymers," specifically distinguishing them from polystyrene (11/19), ABS (30), and other (90). Therefore, 390320 precisely refers to SAN copolymers in primary forms, excluding graft copolymers with rubber (such as ABS) or copolymers with other monomers. This product is classified under 390320 because it is a binary copolymer of styrene and acrylonitrile and is in primary form (such as granules or powder). It differs from 3903.30 (ABS) in that it does not contain a butadiene rubber phase; it differs from 3903.90 (other styrene copolymers) in that it is composed of only two monomers, styrene and acrylonitrile, and the acrylonitrile content is usually less than 50%. If SAN is blended or grafted with rubber, it may be classified under ABS or another code.

Product name: The standard name of the declared commodity should be "styrene-acrylonitrile copolymer in primary forms" or "SAN resin," and common names such as "AS plastic" should be avoided. Appearance: Describe the specific form of the primary form, such as colorless transparent granules, white powder, liquid, etc., and it must be consistent with the definition of "primary forms." Composition content: List the percentages of styrene and acrylonitrile monomers, as well as any additives that may be present (such as antioxidants and lubricants) and their content. Types and proportions of monomer units: Clearly state that the copolymer is composed of two monomer units, styrene and acrylonitrile, and give the molar ratio or weight ratio. Brand: Fill in the registered brand name of the manufacturer or trader; if there is no brand, write "none." Model: Fill in the product grade or model, such as "SAN 350," "Luran 358N," etc., to distinguish different properties. Use: Explain the final application field of the SAN resin, such as home appliance housings, automotive parts, packaging containers, etc. Processing method: State whether it is injection molding grade, extrusion grade, or another type, which helps confirm the primary form status. Product name: Styrene-acrylonitrile copolymer in primary forms (SAN resin); Appearance: colorless transparent granules; Composition content: styrene 75%, acrylonitrile 25%, antioxidant 0.1%; Monomer units: binary copolymer of styrene and acrylonitrile; Brand: LG; Model: SAN 350; Use: used to produce transparent parts for home appliances; Processing method: injection molding grade. Confusing SAN with ABS and failing to declare that it does not contain butadiene, resulting in incorrect classification under 3903.30. Incomplete declaration of composition content, ignoring the acrylonitrile proportion, making it impossible to verify the copolymer type. The appearance description does not reflect "primary forms"; for example, writing "sheet" may easily lead to misclassification under other headings.

The core basis for classification is: 1) the product is in primary form (granules, powder, etc.); 2) it is copolymerized from two monomers, styrene and acrylonitrile, with styrene as the principal monomer; 3) it does not contain butadiene or other rubber components. According to the notes and subheading notes to Chapter 39 of the Import and Export Tariff, 3903.20 applies only to styrene-acrylonitrile copolymers and does not include graft copolymers with rubber (ABS) or copolymers with other monomers. If the acrylonitrile content in the copolymer exceeds 50%, it may be classified under other headings of Chapter 39 or Chapter 29. 3903.30 ABS copolymer: ABS is a styrene-acrylonitrile-butadiene terpolymer containing a rubber phase, while SAN is a binary copolymer that does not contain butadiene. 3903.90 Other styrene copolymers: 3903.90 covers styrene copolymers other than polystyrene, SAN, and ABS, such as styrene-maleic anhydride copolymer, while SAN is composed only of styrene and acrylonitrile. 3903.19 Other polystyrene: Polystyrene is a styrene homopolymer and does not contain acrylonitrile; SAN is a copolymer with a significant acrylonitrile content. 3906.90 Other acrylic polymers: If the copolymerization ratio of acrylonitrile and styrene is abnormal, it may be mistakenly classified as acrylic, but SAN is mainly based on styrene, and acrylonitrile is not an acrylate. 2905.31 Acrylonitrile: Acrylonitrile is a separate organic compound classified under Chapter 29, while SAN is a polymer classified under Chapter 39. Confirm that the product is in primary form (granules, powder, etc.) Confirm that it is copolymerized from two monomers, styrene and acrylonitrile Confirm that it does not contain butadiene or other rubber components Confirm that the acrylonitrile content does not exceed 50% Confirm that it is not blended or grafted with other polymers

How can I check the tax rate for HS code 390320? You can log on to the official website of the General Administration of Customs of China or the International Trade Single Window and enter code 390320 to check the latest import tax rate, value-added tax, and regulatory conditions. Tax rates vary by country, trade agreement, and annual adjustments, so official real-time data should be used as the basis. How can SAN resin and ABS plastic be distinguished during customs declaration? The key difference is whether butadiene is contained. SAN is a styrene-acrylonitrile binary copolymer, while ABS is a styrene-acrylonitrile-butadiene terpolymer. During declaration, the composition content must be provided. If butadiene is detected, it is classified under 3903.30; otherwise, it is classified under 3903.20. If glass fiber is added to SAN resin, how should it be classified? If reinforcing materials such as glass fiber are added and it is still in primary form, it is usually classified as plastic, but it may be necessary to determine whether it is classified under 3903.20 or another heading (such as 3907) based on the fiber content and processing state. It is recommended to consult a professional classification specialist. What is the definition of primary forms? Does SAN resin powder count as primary form? Primary forms refer to unprocessed forms such as liquids, pastes, blocks, powders, and granules. Powder belongs to primary forms. Therefore, SAN resin powder can be classified under 3903.20, but if it has been made into semi-finished products such as sheets or films, it is classified under other headings. What regulatory documents are required to import SAN resin? Basic documents such as contracts, invoices, packing lists, bills of lading, and certificates of origin are usually required. If hazardous chemicals are involved, an MSDS and hazardous goods packaging certificate are required. Specific regulatory conditions can be checked in the customs tariff, and some countries may require import licenses. What are the consequences of mistakenly declaring SAN as ABS? It may lead to incorrect classification, affecting tax rates, regulatory conditions, and statistics. If discovered during customs inspection, it may result in additional tax payments, fines, or even administrative penalties. It is recommended to declare truthfully and, if necessary, apply for advance classification. In the declaration elements for SAN resin, how should the composition content be filled in? The percentages of styrene and acrylonitrile, as well as the types and contents of additives, should be filled in. For example: styrene 75%, acrylonitrile 25%, antioxidant 0.1%. Composition content is key to classification and must be accurate. Do SAN products sold via cross-border e-commerce require customs declaration? If exported via cross-border e-commerce retail, they are usually handled under postal tax or cross-border e-commerce comprehensive tax, but if imported or exported via general trade, formal customs declaration is required and HS code 390320 should be used correctly. It is recommended to choose the declaration channel according to the actual trade method.