CHAPTER 28 · LEGAL NOTES
Chapter 28
The 318 legal notes below govern classification under Chapter 28. They are part of the official Harmonized Tariff Schedule and are cited verbatim in CBP rulings.
As of June 9, 2026
Chapter notes
Note 1
Chapter Note 1: Except where the context otherwise requires, the headings of this chapter apply only to: (a) Separate chemical elements and separate chemically defined compounds, whether or not containing impurities; (b) The products mentioned in (a) above dissolved in water; (c) The products mentioned in (a) above dissolved in other solvents provided that the solution constitutes a normal and necessary method of putting up these products adopted solely for reasons of safety or for transport and that the solvent does not render the product particularly suitable for specific use rather than for general use; (d) The products mentioned in (a), (b) or (c) above with an added stabilizer (including an anticaking agent) necessary for their preservation or transport;
Note 2
Chapter Note 2: In addition to dithionites and sulfoxylates, stabilized with organic substances (heading 2831), carbonates and peroxocarbonates of inorganic bases (heading 2836), cyanides, cyanide oxides and complex cyanides of inorganic bases (heading 2837), fulminates, cyanates and thiocyanates, of inorganic bases (heading 2842), organic products included in headings 2843 to 2846 and 2852 and carbides (heading 2849), only the following compounds of carbon are to be classified in this chapter: (a) Oxides of carbon, hydrogen cyanide and fulminic, isocyanic, thiocyanic and other simple or complex cyanogen acids (heading 2811); (b) Halide oxides of carbon (heading 2812); (c) Carbon disulfide (heading 2813); (d) Thiocarbonates, selenocarbonates, tellurocarbonates, selenocyanates, tellurocyanates, tetrathiocyanatodiamminochromates (reineckates) and other complex cyanates, of inorganic bases (heading 2842);
Note 3
Chapter Note 3: Subject to the provisions of note 1 to section VI, this chapter does not cover: (a) Sodium chloride or magnesium oxide, whether or not pure, or other products of section V; (b) Organo-inorganic compounds other than those mentioned in note 2 above; (c) Products mentioned in note 2, 3, 4 or 5 to chapter 31; (d) Inorganic products of a kind used as luminophores, of heading 3206; glass frit and other glass in the form of powder, granules or flakes, of heading 3207; (e) Artificial graphite (heading 3801); products put up as charges for fire-extinguishers or put up in fire-extinguishing grenades, of heading 3813; ink removers put up in packings for retail sale, of heading 3824; cultured crystals (other than optical elements) weighing not less than 2.5 g each, of the halides of the alkali or alkaline-earth metals, of heading 3824;
Note 4
Chapter Note 4: Chemically defined complex acids consisting of a nonmetal acid of subchapter and a metal acid of subchapter are to be classified in heading 2811.
Note 5
Chapter Note 5: Headings 2826 to 2842 apply only to metal or ammonium salts or peroxysalts. Except where the context otherwise requires, double or complex salts are to be classified in heading 2842.
Note 6
Chapter Note 6: Heading 2844 applies only to: (a) Technetium (atomic No. 43), promethium (atomic No. 61), polonium (atomic No. 84) and all elements with an atomic number greater than 84; (b) Natural or artificial radioactive isotopes (including those of the precious metals or of the base metals of sections and XV), whether or not mixed together; (c) Compounds, inorganic or organic, of these elements or isotopes, whether or not chemically defined, whether or not mixed together; (d) Alloys, dispersions (including cermets), ceramic products and mixtures containing these elements or isotopes or inorganic or organic compounds thereof and having a specific radioactivity exceeding 74 becquerels per gram (0.002 microcurie per gram); (e) Spent (irradiated) fuel elements (cartridges) of nuclear reactors; (f) Radioactive residues whether or not usable.
Note 7
Chapter Note 7: Heading 2853 includes copper phosphide (phosphor copper) containing more than 15 percent by weight of phosphorus.
Note 8
Chapter Note 8: Chemical elements (for example, silicon and selenium) doped for use in electronics are to be classified in this chapter, provided that they are in forms unworked as drawn, or in the form of cylinders or rods. When cut in the form of discs, wafers or similar forms, they fall in heading 3818.
Statistical notes
Note 1
Statistical Note 1: For the purposes of heading 2804, the term "m 3 " (cubic meter) means a standard cubic meter measured at 21° at 760 mm (1013 millibars) pressure. Unit Rates of Duty of Quantity Article Description Stat. Suffix Heading/ Subheading 1 2 General Special I. CHEMICAL ELEMENTS 2801 Fluorine, chlorine, bromine and iodine:
Note 3
Statistical Note 3: 7%1/ thousand m 3 thousand m 3 Isotopically pure rare gases having a purity of 99 30 thousand m 3 thousand m 3
Note 3
Statistical Note 3: 7%1/ 1 Unit Rates of Duty of Quantity Article Description Stat. Suffix Heading/ Subheading 1 2 General Special 2813 Sulfides of nonmetals; commercial phosphorus trisulfide:
Subheading notes
Note 1
Subheading Note 1: For the purposes of subheading 2852.10, the expression "chemically defined" means all organic or inorganic compounds of mercury meeting the requirements of paragraphs (a) to (e) of Note 1 to Chapter 28 or paragraphs (a) to (h) of Note 1 to Chapter
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Classify under Chapter 28 with confidence
TariffLens applies the legal notes above automatically when classifying — citing the relevant note in every GRI reasoning chain.