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-manufactures (such as tubes, plates, and film), and finished products, but excludes rubber, textile materials, etc. Primary forms refer to unprocessed forms such as liquid, paste, block, and powder, which usually require further molding. The notes to this chapter clarify the definition of polymers, the rules for classifying copolymers, and the distinction from chemicals of Chapter 28, Chapter 29, etc., making it a key chapter for the trade classification of chemical products. Heading 3903 specifically refers to styrene polymers in primary forms, including polystyrene (PS), styrene-acrylonitrile copolymers (SAN), acrylonitrile-butadiene-styrene copolymers (ABS), etc. This heading is divided into multiple subheadings by specific type, such as 3903.11 (expandable polystyrene), 3903.19 (other polystyrene), 3903.20 (styrene-acrylonitrile copolymers), 3903.30 (ABS copolymers), and 3903.90 (other). Subheading 3903.90 is a residual category covering other styrene polymers not elsewhere specified, such as styrene-butadiene copolymers (SBS), etc. Code 390390 is a 6-digit HS code. The first 2 digits "39" represent Chapter 39 (plastics and articles thereof); digits 3-4 "03" represent heading 3903 (styrene polymers in primary forms), which is subdivided by polymer type; digits 5-6 "90" represent subheading 3903.90, namely "other" styrene polymers, used to classify styrene polymers not listed in the aforementioned subheadings (such as 3903.11, 3903.19, 3903.20, 3903.30). Therefore, the complete meaning of 390390 is "other styrene polymers in primary forms," a residual subheading applicable to all styrene polymers other than expandable polystyrene, other polystyrene, SAN, and ABS. This product is classified under 390390 because it is a styrene polymer in primary form and does not fall under other specific subheadings under 3903. If it were expandable polystyrene, it should be classified under 3903.11; ordinary polystyrene under 3903.19; SAN under 3903.20; ABS under 3903.30. Only styrene polymers not elsewhere specified (such as SBS, styrene-maleic anhydride copolymers, etc.) are classified under 3903.90. At the same time, it must be ensured that it meets the definition of primary forms in the notes to Chapter 39; if it has been made into plates, sheets, film, etc., it is classified under other headings.

Product name: The specific name of the declared commodity, such as "styrene-butadiene copolymer" or "SBS resin," which must be consistent with the contract and invoice. Appearance: Describe the physical form of the primary shape, such as "white pellets," "transparent blocks," "powder," etc. Composition content: Indicate the proportion of each monomer unit, such as "styrene 70%, butadiene 30%," accurate to the percentage. Types and proportions of monomer units: For copolymers, list the names and respective contents of all monomer units, such as "styrene, butadiene." Brand: Declare the manufacturer's or trader's brand, such as "LG," "Chi Mei," etc.; if there is no brand, fill in "none." Model: Fill in the product grade or model, such as "SBS-792," to facilitate customs identification of the specific variety. Use: Explain the final use of the polymer in primary form, such as "used to manufacture shoe soles," "used to modify asphalt." Date of signing: The date of signing the contract or order, in YYYY-MM-DD format, used for customs valuation and statistics. Product name: styrene-butadiene copolymer (SBS); Appearance: white pellets; Composition content: styrene 70%, butadiene 30%; Types and proportions of monomer units: styrene 70%, butadiene 30%; Brand: none; Model: SBS-792; Use: used to manufacture hot melt adhesive; Date of signing: 2025-03-15. Mistakenly classifying ABS copolymer under 390390, when it should actually be classified under 390330. Failure to distinguish expandable polystyrene (EPS) from ordinary polystyrene, resulting in an incorrect subheading. Classifying expanded polystyrene pellets under 390390, but if already expanded they may be classified under other headings.

The core basis for classification is the notes to Chapter 39 and the subheading structure of heading 3903. First confirm that the product is in primary form (liquid, paste, block, powder, etc.), then confirm that it is a styrene polymer (homopolymer or copolymer, with styrene units having the highest content). Then determine according to the order of subheadings: if it is expandable polystyrene, classify under 3903.11; other polystyrene under 3903.19; styrene-acrylonitrile copolymer under 3903.20; ABS copolymer under 3903.30; if none of the above apply, classify under 3903.90. Attention must be paid to the copolymer classification rule: if styrene is copolymerized with other monomers and the styrene unit content is the highest, classify under 3903; if the content of other monomer units is higher, classify under other headings. 390311 Expandable polystyrene: 390311 specifically refers to expandable polystyrene (EPS), that is, polystyrene that has not yet expanded but contains a blowing agent; while 390390 covers other styrene polymers not elsewhere specified, such as SBS. If the product is EPS, it must be classified under 390311. 390319 Other polystyrene: 390319 refers to polystyrene homopolymers other than expandable, such as general-purpose polystyrene (GPPS) and high-impact polystyrene (HIPS); while 390390 is for copolymers or other polymers not elsewhere specified. If it is pure polystyrene, it should be classified under 390319. 390320 Styrene-acrylonitrile copolymer: 390320 specifically refers to SAN copolymer, that is, a copolymer of styrene and acrylonitrile; while 390390 covers other copolymers, such as SBS. If it is SAN, it must be classified under 390320. 390330 ABS copolymer: 390330 specifically refers to acrylonitrile-butadiene-styrene copolymer (ABS); while 390390 is for other styrene copolymers. If it is ABS, it should be classified under 390330. 390410 Polyvinyl chloride: 390410 is polyvinyl chloride in primary forms, different from styrene polymers. If the product is PVC, it should be classified under 390410, not 390390. Is it in primary form? Is styrene the monomer unit with the highest content? Does it belong to EPS, ordinary PS, SAN, or ABS? Has it already been expanded or made into another form? Does it conflict with other headings (such as 3901-3914)?

How can I check the import tariff rate for 390390? You can use the official website of the General Administration of Customs, China International Trade Single Window, or third-party inquiry platforms. Enter HS code 390390, select the destination country and country of origin, and the most-favored-nation rate, agreement rate, etc. will be displayed. Note that tariff rates may be adjusted with policy changes, and the latest published version should prevail. What is the difference between 390390 and 390319? 390319 refers to other polystyrene homopolymers (such as GPPS and HIPS), while 390390 refers to other styrene polymers, usually copolymers or polymers not elsewhere specified. If the product is pure polystyrene, it should be classified under 390319; if it is a copolymer of styrene and butadiene (SBS), then classify under 390390. Which HS code should SBS resin be classified under? SBS (styrene-butadiene-styrene block copolymer) is a styrene polymer, and the styrene unit content is usually the highest. It is not listed under other specific subheadings, so it should be classified under 390390. When declaring, the monomer unit proportions and use must be indicated. When declaring 390390, how should the composition content be filled in? The chemical names and mass percentages of all monomer units must be listed, such as "styrene 70%, butadiene 30%." If additives (such as stabilizers) are contained, their content should also be indicated. Composition content is the key to determining classification and must be accurate. Can products under 390390 enjoy agreement tariff rates? Yes, but they must meet the agreement rules of origin. For example, when importing from ASEAN, a FORM E certificate of origin must be provided, and the product must meet the origin criteria of the China-ASEAN Free Trade Agreement. The specific rate must be checked in the latest agreement tariff schedule. If the styrene polymer has already been made into sheets, can it still be classified under 390390? No. 390390 applies only to primary forms. If it has been made into plates, sheets, film, etc., it should be classified under subsequent headings in Chapter 39, such as 3920 (plates, sheets, film of non-cellular plastics). Classification must be determined according to the state of processing. What are the regulatory conditions for 390390? Usually there are no special regulatory conditions, but import licenses, anti-dumping duties, etc. may be involved. For example, certain styrene polymers may be subject to anti-dumping duties, and announcements from the General Administration of Customs should be checked. It is recommended to verify the latest regulatory requirements before customs declaration. How can one determine whether styrene is the monomer unit with the highest content? It must be determined based on the weight percentage of all monomer units in the polymer. If the styrene unit content is the highest, classify under 3903; if the content of other monomers (such as butadiene) is higher, it may be classified under other headings (such as 4002). An accurate composition analysis report should be provided at the time of declaration.