Chemistry HS Codes: Using CAS Numbers

Chemical imports are a high-risk classification area. Chapter 29 alone (organic chemicals) contains thousands of subheadings, often naming individual compounds. The CAS Registry Number is the unique identifier chemists use; the HS uses chemical names that may or may not match the conventional name. Finding the right tariff line for a specific compound requires cross-referencing the CAS number to the chemical name and then to the HS structure.

This guide explains the chapter structure for chemistry products, how to use CAS numbers in the lookup, and the TSCA and CBP considerations that often dominate the actual cost.

Chapters that cover chemistry

The dominant chapters for pure chemicals are 28 and 29. For formulated products (pharmaceuticals, cosmetics, paints, fertilizers), the use-specific chapters apply.

Chapter 29 structure

Chapter 29 is organized by chemical class:

• 2901-2904: hydrocarbons, halogenated hydrocarbons, sulphonated/nitrated/nitrosated derivatives.
• 2905-2909: alcohols, phenols, ethers, peroxides.
• 2910-2914: epoxides, acetals, aldehydes, ketones.
• 2915-2918: carboxylic acids, anhydrides, esters.
• 2919-2926: phosphoric esters, salts of inorganic acids, nitrogen-function compounds.
• 2927-2934: heterocyclic compounds (organic) including amines, amides, nitriles.
• 2935-2940: sulphonamides, organo-sulphur compounds.
• 2941-2942: antibiotics, other organic compounds.

Within each subheading, individual compounds are named or described by structural feature. Example: 2916.32 covers benzoyl peroxide. 2922.41 covers lysine and its salts.

Finding a code by CAS number

The CAS Registry Number is unique per compound. The HS does not list CAS numbers but the chemical name. To go from CAS to HS:

1. Look up the chemical name from the CAS number in PubChem, ChemSpider, or Sigma-Aldrich.
2. Identify the chemical class (alcohol, carboxylic acid, amine, etc.).
3. Look up the class in the chapter 29 structure (or chapter 28 for inorganics).
4. Drill down to the specific subheading for the compound or its class.
5. Extend to the 8-digit national code for duty rate.

Example: aspirin (acetylsalicylic acid, CAS 50-78-2). PubChem identifies it as an acetylated phenolic carboxylic acid. Chapter 29, heading 2918 (carboxylic acids with phenolic functions), subheading 2918.22 covers o-acetylsalicylic acid, its salts and esters. US HTSUS extends to 2918.22.10 for aspirin specifically.

Pure compound vs preparation

The HS distinguishes the pure compound (chapter 28/29) from the preparation (chapter 30+).

• Acetylsalicylic acid as an active pharmaceutical ingredient (API): chapter 29, 2918.22.
• Aspirin tablets formulated for human consumption: chapter 30, 3004.

The form of presentation often determines the chapter:

• Bulk powder in barrels: chapter 29.
• Tablets in retail bottles: chapter 30.
• Tablets in bulk for further repacking: chapter 30 (intended for end use).

Mixed formulations (e.g., aspirin + caffeine): chapter 30 if therapeutic, chapter 21 if a food, chapter 38 if industrial chemical mixture.

Worked example: importing 5,000 kg of D-glucose into Germany

D-glucose (CAS 50-99-7). Chapter 29: heading 2940 (sugars, chemically pure other than sucrose, lactose, etc.). Subheading 2940.00. EU CN code 2940.00.00. MFN rate around 0 percent (low specific duty or zero depending on the year).

If the importer is VAT-registered, VAT is recoverable. Effective cost: zero duty, neutral VAT.

Worked example: importing 50,000 USD of paracetamol API into India

Paracetamol (acetaminophen, CAS 103-90-2). Chapter 29: heading 2924 (carboxyamide-function compounds). Subheading 2924.29 (other cyclic amides). India HSN extends to 2924.29.23 for paracetamol.

India MFN duty: 7.5 percent. Basic customs duty: 7.5 percent. Social welfare surcharge: 10 percent of BCD = 0.75 percent. IGST (Integrated GST): 12 percent on assessable value plus duty.

The pharmaceutical company recovers the IGST through GST credits. Effective duty around 8.25 percent.

TSCA in the US

The Toxic Substances Control Act (TSCA) requires every chemical imported into the US for commercial purposes to be either:

• On the TSCA Inventory (about 86,000 chemicals listed).
• The subject of an active Pre-Manufacture Notice (PMN) that has cleared.
• Specifically exempt (research, low-volume, polymer exemption, etc.).

The importer must file a Section 13 import certification (TSCA-positive or TSCA-negative) with each shipment. The TSCA-positive certification states the chemical is on the inventory or otherwise permitted. The TSCA-negative certification states the chemical is for an excluded use (research, non-TSCA use).

A misclassified TSCA certification can lead to import refusal at the port and EPA enforcement actions far exceeding any duty calculation.

REACH in the EU

The EU REACH regulation requires registration of any chemical imported into the EU in quantities over 1 tonne per year. Registration is not optional for commercial imports; it must be in place before import.

For chemicals imported into the EU, the importer must be:

• The EU manufacturer's only representative if the producer is non-EU.
• A registered importer holding a current REACH dossier for the substance.

REACH dossiers are expensive (six to seven figures for full registration). For small importers, the manufacturer is the natural REACH holder.

High-friction categories

• Restricted precursors (chapter 28, 29): pseudoephedrine, ephedrine, ergometrine, ergotamine, lysergic acid, norephedrine. Subject to ATF and DEA import permits.
• CITES chemicals (chapter 13 plant extracts, chapter 29 derivatives of CITES species): require CITES permits.
• Ozone-depleting substances (Montreal Protocol): chapter 29 hydrochlorofluorocarbons, hydrofluorocarbons. Subject to Montreal Protocol licensing.
• Persistent Organic Pollutants (Stockholm Convention): chapter 29 and 38, certain compounds. Import restricted or banned.
• Conventional Weapons Convention chemicals (chapter 29): certain compounds covered. State Department licensing.

How the calculator handles chemistry

The LandedFees HS lookup tool for chemicals:

• Accepts a chemical name or CAS number.
• Maps to the relevant HS chapter and heading.
• Surfaces the duty rate and Section 122 applicability.
• Notes TSCA, REACH, and other regulatory hooks.
• Cross-references CBP CROSS rulings on similar chemicals.

Section 122 status as of June 20 2026

The May 7 2026 Court of International Trade ruling in Oregon v. United States (consolidated with Burlap and Barrel v. United States) struck down the Section 122 proclamation. The Federal Circuit issued an administrative stay on May 12 2026, so CBP is still collecting the duty pending appeal. Importers paying now should preserve protest rights and refund claims in case the government loses on the merits. The underlying Section 122 authority sunsets July 24 2026 under the statutory 150-day ceiling, regardless of the appeal outcome, unless Congress extends or a fresh proclamation restarts the clock.

Related guides

• HS Code Lookup: How to Find Yours
• Pharma HS Codes and FDA Requirements
• Cosmetics: HS Codes + MoCRA
• Calculate Import Duty: India to USA
• Restricted Products: A Plain-English Guide
• 10 Most Misclassified HS Codes (and how to fix them)

Try the LandedFees HS lookup tool for chemical classification.