9902.01.23 - Hypophosphorous acid 50% (phosphinic acid) (CAS No. 6303-21-5) (provided for in subheading 2811.19.61)

This HTS category, 9902.01.23, specifically covers hypophosphorous acid at a 50% concentration, also known as phosphinic acid, bearing the CAS number 6303-21-5. It is important to note that while this code provides a specific classification for this particular chemical, its inclusion under Chapter 99 indicates it is subject to temporary legislation, trade agreement modifications, or additional import restrictions proclaimed under Section 22 of the Agricultural Adjustment Act. This temporary nature means its tariff treatment may differ from its permanent classification under Chapter 28.

Distinguishing this category from its many sibling categories at the HTS database root level requires an understanding of the fundamental principles of the Harmonized Tariff Schedule. While siblings at the first two digits (e.g., Chapters 01, 02, 03) often classify live animals or agricultural products based on species or type, Chapter 99 is reserved for specific, often temporary, tariff treatments. Therefore, the primary distinguishing factor here is the regulatory status and temporary nature of the classification, rather than the inherent physical or biological characteristics of the goods themselves. This code is not a general classification for all acids, but rather a specific provision for hypophosphorous acid under special circumstances.

As this node represents a leaf node within the HTS structure, there are no further subcategories. Classification within this specific code is definitive for the described product when it meets the conditions outlined by the temporary legislation or proclamations associated with Chapter 99. Importers should therefore refer to the accompanying notes and directives for Chapter 99 and specifically for subheading 9902.01.23 to understand the full scope of its application, including any specific documentation, quantity limitations, or duty rates that may apply.