Diphosphorus pentaoxide — HTS 2809
Diphosphorus pentaoxide; phosphoric acid;polyphosphoric acids, whether or not chemically defined
Chapter 28 › Heading 2809
2026 HTS Rev 19 Synced Rules verified Operational
Written to help non-specialists understand this page. Rates, dates, and legal facts come from the official records above and on the linked source.
HTS heading 2809 is a 4-digit product category for certain phosphorus-based inorganic chemicals. It groups together diphosphorus pentaoxide (also called phosphorus pentoxide), phosphoric acid, and polyphosphoric acids, including products that may contain related forms that are not chemically defined as a single pure compound.
The heading is only the starting point, not the complete classification. To reach the correct 8-digit HTSUS code, first identify the substance and its chemical form, then follow the applicable subheading descriptions. The narrower code may distinguish among diphosphorus pentaoxide, phosphoric acid, and different polyphosphoric-acid products, as well as other stated characteristics. Confirm the classification using the current HTSUS text, the General Rules of Interpretation, and the product’s technical evidence; a customs broker or classification specialist may be needed for mixtures or unusual formulations.
What to check
- Check the product’s exact chemical identity, including whether it is diphosphorus pentaoxide, phosphoric acid, or a polyphosphoric acid.
- Review the safety data sheet, certificate of analysis, specification sheet, and label for concentration, composition, and chemical form.
- Read every 8-digit subheading under heading 2809 and match the product to the most specific description; do not stop at the 4-digit heading.
- Determine whether additives, water, mixtures, or chemically undefined components affect classification under the HTSUS rules.
- Keep records supporting the classification and ask a customs broker or qualified tariff specialist to review borderline or technically complex products.
HTS heading 2809 summary
Diphosphorus pentaoxide is a 4-digit product category containing 2 published product-code lines in this snapshot. A heading does not carry one universal duty rate; classification must be narrowed to the line matching the product facts.
How to find your code in this category
A heading is a product category. To get the exact duty, narrow from this 4-digit heading to a sub-category (usually by material), then open the 8-digit code that matches your product.
Open any code in the tables below to see its exact duty rate, a duty calculator (enter your shipment value → estimated duty and landed cost), the rate-change history chart, and the country-by-country breakdown (including Section 301/232 add-on duties).
Why you have to click in: a single category can contain products with very different duties. The rate depends on the specific product — its material and construction — and on the country of origin, and those only get pinned down at the 8-digit code level. That is why this page points you to codes instead of showing one rate for the whole category.
Product codes & duty rates
👇 Each row is a specific product code — click a blue code to open its full page with exact duty rates by country, the rate-history chart, and a duty calculator. 👉
| Code | Description | General (MFN) | Special | Column 2 |
|---|---|---|---|---|
| 2809.10.00.00 👉 | Diphosphorus pentaoxide | Free | — | 25% |
| 2809.20.00 👉 | Phosphoric acid and polyphosphoric acids | Free | — | Free |
"Special" shows the free-trade-agreement rate; open a code to see exactly which countries qualify.
Common questions
What products fall under HTS heading 2809?
Diphosphorus pentaoxide; phosphoric acid;polyphosphoric acids, whether or not chemically defined. To classify a specific item you must pick the matching sub-category and 8-digit code above; the right choice usually depends on the material and construction of the product.
How do I choose the right code within this category?
Start from the sub-categories (typically divided by material—for example cotton versus man-made fibers), then open the active 8- or 10-digit code that matches the product. When unsure, a licensed customs broker or a CBP binding ruling can confirm the classification.
Reference information only, not customs, legal, or classification advice. Confirm the current code and rate against the official HTS before you import.