Sulfur Trioxide
Sulfur trioxide (SO3) is a colorless to white crystalline solid or liquid, used as a sulfonating agent and in the production of sulfuric acid. As the anhydride of sulfuric acid, it is a chemically defined inorganic oxygen compound of the non-metal sulfur, classified under tariff item 2811.29.00. It is often supplied stabilized to prevent polymerization, which is acceptable under Chapter 28 note 1(d).
Import Duty Rates by Country of Origin
| Origin Country | MFN Tariff | Surtaxes | Total Effective Rate |
|---|---|---|---|
| 🇨🇳China | Free | — | Free |
| 🇲🇽Mexico | Free | — | Free |
| 🇺🇸United States | Free | — | Free |
| 🇩🇪Germany | Free | — | Free |
| 🇯🇵Japan | Free | — | Free |
Alternative Classifications
This product could be classified differently depending on its characteristics or intended use.
If the product is sulfuric acid or oleum rather than pure sulfur trioxide
Sulfuric acid is a separate heading; the anhydride is distinct.
If the product is a hydrogen halide acid
Not applicable to sulfur trioxide, but listed for completeness.
Not sure which classification is right?
The Tariff Assistant works through the GRI rules on your specific product to reach the right tariff item — and can price the duty on it in the same conversation.
Import Tips & Compliance
• Verify the stabilizer used does not render the product suitable for a specific use, as that could affect classification
• Sulfur trioxide is hazardous; ensure proper shipping documentation and safety data sheets are provided to the CBSA
• Confirm the product is not in a form that falls under heading 28.07 (sulfuric acid) if it is hydrated
Related Products under Tariff item 2811.29.00
ACS Reagent Selenium Dioxide
ACS reagent grade selenium dioxide for high-precision analytical and research applications. It is a pure, chemically defined inorganic oxygen compound of the non-metal selenium, meeting Chapter 28 note 1 requirements.
Anhydrous Sulfur Dioxide for Wine Preservation
High-purity anhydrous sulfur dioxide gas used in winemaking to prevent oxidation and microbial growth. This chemically defined inorganic oxygen compound of sulfur meets the Chapter 28 criteria for separate chemical compounds, whether or not containing impurities. Supplied in pressurized containers for direct use in wine preservation.
Antimony Trioxide
Antimony trioxide (Sb₂O₃) used as a flame retardant in plastics and a catalyst in PET production. This fine white powder is an inorganic oxygen compound of the non-metal antimony, classified under Chapter 28. The product is a chemically defined compound in its pure form.
Arsenic Trioxide
Arsenic trioxide (As₂O₃), a white powder used in pharmaceuticals and glass production, is an inorganic oxygen compound of the non-metal arsenic. This chemically defined compound falls under Chapter 28 as an 'other' inorganic oxygen compound of non-metals. The product is supplied in pure form for various industrial applications.
Arsenic Trioxide Anhydrous Powder
Arsenic trioxide (As2O3) in anhydrous powder form, a white crystalline inorganic compound. It is a chemically defined inorganic oxygen compound of the non-metal arsenic, used primarily in industrial applications such as glass production and metallurgy.
Arsenic Trioxide Flake Form
Arsenic trioxide in dense flake form, used for easier handling in metallurgy and glass decolorizing processes. It is a chemically defined inorganic oxygen compound of the non-metal arsenic, falling under this tariff item.