Chapter 29, 38 or 39? Classifying chemicals and plastics by the notes

Short answer: A chemical goes to Chapter 28 or 29 only if it is a separate chemically defined compound within Chapter 29 Note 1 (or Chapter 28 Note 1), which allows impurities, water or a transport solvent, stabilizers and identification additives, but nothing that makes the product suited to a specific use. Once it fails that test it becomes a preparation, and Chapter 38 Note 1(a) opens heading 3824 or a more specific Chapter 38 heading. Polymers go to Chapter 39 by the predominant comonomer (Chapter 39 Note 4) when they are in primary forms (Note 6), and two-part products put up to be mixed follow Section VI Note 3. A CAS Registry Number tells you which substance is in the drum, but these notes, not the number, decide the code.

Chemical product records usually hold a trade name and one CAS number, but the heading depends on everything else in the drum: solvent, additives, polymer ratio, physical form and packaging. Below is the order in which the notes apply, with an example at each step, and the separate export control question at the end.

Why do the notes decide chemical classification?

Chemical classification is decided at GRI 1, which reads the heading texts together with the section and chapter notes, and in Sections VI and VII the notes do most of the work. The general method for any product is in how to classify a product from description to HTS code; this article covers the chemistry-specific rules.

Section VI starts with two priority rules. Note 1 sends radioactive and isotope goods described in headings 2844 and 2845 to those headings first, then goods described in 2843, 2846 and 2852. Note 2 says goods classifiable in certain headings “by reason of being put up in measured doses or for retail sale” (including 3004, 3303 to 3307, 3506 and 3808) are classified there and nowhere else. A pure compound in a retail pack can therefore leave Chapter 29 for a use heading.

What is the decision order for a chemical or plastic?

Run these questions in order and stop at the first one that places the product:

Do Section VI Notes 1 or 2 apply (isotopes, precious-metal compounds, retail or dosed put-ups of the listed headings)? If yes, those headings take it.
Is it two or more separate constituents put up to be mixed into one product? If yes, apply Section VI Note 3.
Is it a separate chemically defined compound, with only the additions Chapter 28 or 29 Note 1 allows? If yes, it stays in Chapter 28 (inorganic) or 29 (organic).
Is it a polymer of the kinds in Chapter 39 Note 3, in a primary form under Note 6? If yes, apply Note 4 to find the heading among 3901 to 3914.
Is it a preparation that a specific heading names (colorant preparations in Chapter 32, solvent blends in 3814, disinfectants in 3808, plastics additives in 3812)? If yes, use that heading.
Otherwise, a chemical preparation not elsewhere specified goes to heading 3824.

What counts as a separate chemically defined compound?

A separate chemically defined compound is a single substance with a defined molecular structure, such as acetone or isopropyl alcohol. Chapter 29 Note 1(a) limits the chapter’s headings to these compounds, “whether or not containing impurities.” Note 1(b) adds mixtures of isomers of the same compound (except acyclic hydrocarbon isomers, which go to Chapter 27), and Note 1(c) adds certain groups such as provitamins and vitamins (2936), hormones (2937), glycosides (2938), alkaloids (2939) and antibiotics (2941), whether or not chemically defined. Chapter 28 Note 1 sets the same frame for inorganic chemicals.

“Impurities” has a narrow meaning. In the Explanatory Notes, an impurity is something present only because of the manufacturing process: unreacted starting material, a by-product, residual catalyst. A substance added on purpose is not an impurity, whatever its percentage. A “99% pure” certificate answers half the question; you also need to know what the other 1% is and why it is there.

What may a Chapter 29 compound contain and still stay there?

Chapter 29 Note 1(d) to (h) then extend the chapter to compounds in these conditions:

1(d): water, as a solvent.
1(e): another solvent, but only when dissolving the compound is the normal way to ship it safely, done purely for safety or transport, and the solvent does not fit the product for one particular use.
1(f): a stabilizer, including an anticaking agent, “necessary for their preservation or transport.”
1(g): an anti-dusting agent, or a coloring, odoriferous substance or emetic added for identification or safety, again only if the product is not made suitable for a specific use.
1(h): diazonium salts, couplers and diazotizable amines diluted to standard strengths for making azo dyes.

Every addition on that list keeps the compound safe, stable or identifiable. None makes it perform. That gives a working test for any addition: was it put there for the drum, or for the customer’s process? Chloroform with a small amount of stabilizer to slow decomposition in storage stays a Chapter 29 compound. The same compound with a surfactant added so it cleans better is a preparation.

Worked example, using isopropyl alcohol: 99.8% isopropyl alcohol in 200-liter drums is classified in 2905.12, which names propan-2-ol, under Note 1(a). A 70% solution of isopropyl alcohol in water, still in drums, stays in 2905.12 because Note 1(d) allows the compound to be dissolved in water. Fill that same 70% solution into 500 ml bottles labeled as a surface disinfectant and Section VI Note 2 takes over: heading 3808 covers disinfectants put up in forms or packings for retail sale, and the bottles go to 3808.94.

How far does a CAS Registry Number get you?

A CAS Registry Number (CAS RN) gets you to the right substance, which is the first half of classifying a chemical. Chemical Abstracts Service (CAS) assigns one number to each substance it registers: up to 10 digits in three hyphenated parts, the last of which is a check digit. In CAS’s words, a CAS RN “designates only one substance,” and the number does not depend on any naming system. Isopropyl alcohol, propan-2-ol, 2-propanol and IPA are all CAS RN 67-63-0, so the number settles what a supplier’s trade name, a translated SDS and an old item master each call the product. A salt is a separate substance from its parent compound and has its own number; metformin hydrochloride, for example, is CAS RN 1115-70-4.

The CAS RN does not decide the HS code. Go back to the isopropyl alcohol example: the 99.8% drum, the 70% aqueous solution and the 500 ml bottles of disinfectant all carry CAS RN 67-63-0 on their safety data sheets, and they classify in 2905.12, 2905.12 and 3808.94. The number says nothing about what else is in the container or why, which is what Chapter 29 Note 1 tests. It says nothing about retail put-up (Section VI Note 2), physical form (the same polymer is in 3901 as pellets and 3920 as film) or the monomer weight split that Chapter 39 Note 4 needs for a copolymer. One CAS RN can therefore map to several HS codes, and a preparation listing four CAS RNs on its SDS is classified as a preparation, not under whichever component is largest.

For a free CAS-to-tariff reference, check the European Customs Inventory of Chemical Substances (ECICS), run by the European Commission’s Directorate-General for Taxation and Customs Union (DG TAXUD) and open to anyone. Each ECICS entry gives the substance’s names in EU languages, its CAS RN, a CUS number assigned by DG TAXUD and its eight-digit Combined Nomenclature (CN) code. The first six digits of a CN code are the HS subheading, so an ECICS entry is a usable 6-digit reference for a US import as well. The Commission states two limits: ECICS “mainly contains pure chemicals,” and its information “is not binding and does not give rise to protection of any kind.” Treat an ECICS code as the classification of the pure substance, then run Note 1 on the product you actually ship.

You can send CAS RNs with the rest of your product data to TariffWolf. It reads them together with the composition by weight, the purpose of each addition, the physical form and the packaging, asks for whichever of those is missing, and returns the 6-digit HS code with the chapter note, GRIs and rulings that placed the product. Your classifier or customs broker then chooses the last four digits of the HTS line.

When does a chemical move to 3824 or another Chapter 38 heading?

A chemical moves to Chapter 38 when it is no longer a separate chemically defined compound. Chapter 38 Note 1(a) closes the chapter to “separate chemically defined elements or compounds,” with a short list of exceptions such as artificial graphite, certified reference materials and products put up as described in heading 3808. Chapter 38 and Chapters 28 and 29 are mirror images: a product cannot be in both.

Heading 3824 is the residual heading for chemical products and preparations, including mixtures of natural products, that no other heading covers. The words “not elsewhere specified or included” mean the named Chapter 38 headings come first. A blend of acetone and toluene sold as a thinner is an organic composite solvent of heading 3814, not a 3824 preparation, while acetone alone is 2914.11. Older rulings on 3824 preparations may cite subheading 3824.90, which no longer exists; the residual lines now sit under 3824.99, so re-check any subheading taken from a ruling before it goes on an entry.

How do Chapter 39 Notes 4 and 6 classify polymers?

Headings 3901 to 3914 cover plastics in primary forms, and two notes decide almost every case. Chapter 39 Note 4 defines a copolymer as a polymer in which no single monomer unit contributes 95% or more by weight, and sends copolymers and polymer blends to the heading for whichever comonomer unit outweighs each of the others. Comonomer units whose polymers fall in the same heading are added together, and if nothing predominates, the heading last in numerical order wins. Note 6 limits “primary forms” to two groups: liquids and pastes, including dispersions and solutions; and bulk forms such as powders, granules, flakes, lumps and irregular blocks.

Take ethylene-vinyl acetate pellets with 82% ethylene and 18% vinyl acetate by weight. Ethylene predominates, so the heading is 3901 (polymers of ethylene), and the subheading is 3901.30, which names ethylene-vinyl acetate copolymers. Pellets are granules, so Note 6 is met. Extrude the same polymer into film and it leaves the primary-form headings for 3920 (other plates, sheets, film, foil and strip).

Masterbatches show why the notes, not weight, have the last word. A white masterbatch of 60% titanium dioxide in a polyethylene carrier is mostly by weight a preparation in plastic, yet Chapter 32 Note 3 extends headings 3203 to 3206 to “preparations based on coloring matters of a kind used for coloring any material.” A pigment concentrate made to color plastics in the mass fits that description, which points the white masterbatch to heading 3206 (titanium dioxide preparations under 80% go to 3206.19). An additive masterbatch with no colorant, such as a slip or UV-stabilizer concentrate, has no Chapter 32 note to pull it, and the analysis returns to 3812, 3824 or the carrier polymer’s heading in Chapter 39. CBP drew the same line in NY N245713 (September 26, 2013): a white polyethylene masterbatch went to 3206.19 and a black one to 3206.49, while the same importer’s antiblock and process-aid masterbatches went to heading 3812.

Is a two-part epoxy a set under Section VI Note 3?

A two-part epoxy is classified as the finished, mixed product when it meets Section VI Note 3. The note covers goods “put up in sets consisting of two or more separate constituents,” some or all of them in Section VI, that are “intended to be mixed together to obtain a product of section VI or VII.” Three conditions apply: the packaging must show the constituents are meant to be used together as they come, without repacking; they must arrive in the same entry; and their nature or proportions must show that each completes the other.

A 50 ml dual-barrel syringe with an epoxide resin on one side, an amine hardener on the other and a mixing nozzle meets all three conditions. The mixed product is an adhesive, and because the pack is sold as an adhesive and weighs under 1 kg, it falls in 3506.10 (glues and adhesives “put up for retail sale as glues or adhesives, not exceeding a net weight of 1 kg”). The same resin and hardener shipped in separate bulk drums to a formulator fail the conditions; the resin goes to 3907.30 (epoxide resins) and the hardener is classified by its own chemistry. Note 3 is a Section VI rule. It is not GRI 3(b), and essential character plays no part in it.

Do chemicals need an export control check as well?

Chemicals need a separate export control determination, and the HTS code does not answer it. On the Commerce Control List, ECCN 1C350 covers chemicals that can be used as precursors for toxic chemical agents, and mixtures containing them above set concentrations; ECCN 1C355 covers Chemical Weapons Convention (CWC) Schedule 2 and 3 chemicals not already controlled by 1C350. The CWC adds its own paperwork in 15 CFR Part 745: exports of Schedule 1 chemicals need advance notice to the Bureau of Industry and Security (BIS) and an annual report, and Schedule 3 chemicals going to countries outside the CWC need an end-use certificate from the importing government. Exports from the EU follow the matching entries in Category 1 of Annex I to the EU Dual-Use Regulation, and Indian exporters check Category 1 of the SCOMET list.

Because the control lists name chemicals by CAS number and concentration, a product that moved from Chapter 29 to 3824 on the tariff side can still be controlled on the export side. Run the two classifications from the same composition data. The parameter-by-parameter method for finding an ECCN is in how exporters pin down an ECCN.

What mistakes do chemical importers make?

Classifying from the CAS number of the main ingredient and ignoring the solvent and additives.
Treating a performance additive as a stabilizer. Note 1(f) covers stabilizers “necessary for their preservation or transport,” not additives that improve the product in use.
Going straight to 3824 without checking the named Chapter 38 headings or Chapter 32 Note 3.
Classifying a copolymer by its name (“acrylic”) rather than by the monomer weight split.
Applying Section VI Note 3 to components that arrive in separate bulk shipments.

Most of these errors come from missing data. A composition sheet with percentages by weight and one line on why each component is there prevents the first three.

Frequently asked questions

Does adding a stabilizer change a chemical’s HTS classification?

A stabilizer does not change the classification if it is necessary for preservation or transport, because Chapter 29 Note 1(f) and the matching Chapter 28 note allow it. An additive that makes the product suitable for a specific use turns it into a preparation, usually in Chapter 38.

Can you find the HS code from a CAS number?

A CAS number identifies the substance and gives you a starting point, but it does not decide the HS code on its own. The same CAS number can classify in Chapter 29, Chapter 38 or a retail heading such as 3808, depending on purity, added components, form and packaging. The EU’s ECICS database lists CN codes for many pure chemicals by CAS number; its entries are not binding.

What goes in heading 3824?

Heading 3824 is the catch-all for chemical products and preparations that no other heading names. It takes mixtures and preparations that are not separate chemically defined compounds and that no more specific heading, such as 3814 for solvent blends or 3812 for plastics stabilizers, describes.

How is a copolymer classified in Chapter 39?

Under Chapter 39 Note 4, a copolymer goes to the heading for the comonomer unit that is heavier than any other single unit. Units whose polymers share a heading are counted together, and if none predominates, the last heading in numerical order applies. The polymer must also be in a primary form under Note 6.

Is a two-part epoxy classified as a set?

A two-part epoxy is classified as the mixed product under Section VI Note 3 when the resin and hardener come packed for use as they are, arrive in the same entry and are clearly made for each other. A retail dual syringe of epoxy adhesive under 1 kg goes to 3506.10; resin and hardener shipped in separate bulk drums are classified separately.

Before you code a chemical, get the composition by weight and the reason for every component, and write down which note placed the product. That note reference is what you will need if CBP asks, and it is the first thing to re-check when a supplier changes the formulation.

For chemical and plastics catalogs, TariffWolf’s bulk classification service gives you the 6-digit HS subheading for each product with the chapter note and rulings behind it, routes formulations with missing data to a classifier, and leaves the final four HTS digits to your team or broker. Send a sample of difficult products, CAS RNs included, and review the reasoning before a full run.

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