HS Code for Trimethyl phosphite

Trimethyl phosphite is classified under HS code 2920.23. This classification is found in Chapter 29 (Organic Chemicals), specifically under Heading 2920, which covers esters of inorganic acids. Trimethyl phosphite is the trimethyl ester of phosphorous acid. The Harmonized System provides specific subheadings for various phosphite esters to assist in the regulation of chemicals that have both industrial and potential military applications. Subheading 2920.23 is the unique identifier for trimethyl phosphite. It is a colorless liquid with a pungent odor, used primarily as a reagent in organic synthesis and as an intermediate in the production of organophosphorus pesticides and flame retardants. Because it is a precursor for the synthesis of certain nerve agents, it is strictly monitored under the Chemical Weapons Convention (CWC). Importers and exporters must use HS code 2920.23 to ensure that the shipment is correctly identified by national authorities responsible for non-proliferation. The classification applies to the chemical in its pure form or as a separate chemically defined compound.

Products Included

• Trimethyl phosphite (TMP) technical grade
• Trimethyl phosphite for agrochemical production
• High-purity TMP for laboratory synthesis
• Trimethyl phosphite used as a polymer stabilizer

Common Misclassification

Trimethyl phosphite is frequently confused with Triethyl phosphite (2920.24). While they share similar chemical properties, the difference in the alkyl group requires distinct classification. It is also sometimes incorrectly placed in 2931.39, which is a residual category for other organo-phosphorus compounds. However, since TMP is an ester of phosphorous acid, it is specifically directed to Heading 2920 by the HS Explanatory Notes.

FAQ

What is the HS code for Trimethyl phosphite?

The international HS code for Trimethyl phosphite is 2920.23, located within the section for esters of inorganic acids.

Does Trimethyl phosphite require an export license?

In many jurisdictions, yes. Because it is a CWC Schedule 3 chemical, exports of 2920.23 often require specialized permits and end-user statements.