Sulphur trioxide (sulphuric anhydride)

Sulphur trioxide, sulphuric anhydride (inorganic oxygen compound)

CBIC CLEARANCE

HSN 2811 29 50 (Sulphur trioxide / sulphuric anhydride) is subject to Central Board of Indirect Taxes and Customs (CBIC) mandatory additional-qualifier requirements under CBIC Circular 23/2023-Cus dated 30-09-2023, applicable to all commodities under Chapter 28. Imports exceeding specified hazardous quantities additionally attract a statutory insurance obligation under the Public Liability Insurance Act, 1991, as notified by the Ministry of Environment and Forests vide S.O. 227(E) dated 24-03-1992.

What this is

HSN code

2811 29 50

Chapter

28 · Inorganic chemicals; organic or inorganic compounds of precious metals

Primary regulator

CBIC · Mandatory Chapter 28 qualifiers, CBIC Circular 23/2023-Cus

Customs documentation

Chapter 28 qualifiers from CBIC
Insurance policy from insurer
Hazardous-quantity declaration to CBIC

Compliance steps

1
File mandatory additional qualifiers in the import declaration for Chapter 28 commodities as stipulated in paragraphs 4.1 and 4.2 of CBIC Circular 23/2023-Cus. These qualifiers became compulsory with effect from 15 October 2023 and non-compliance renders the bill of entry liable to rejection or detention at first assessment.
CBIC Circular 23/2023-Cus dated 30-09-2023, paragraphs 4.1 and 4.2
2
Where the import quantity of sulphur trioxide exceeds the threshold specified under the Public Liability Insurance Act, 1991, obtain and maintain a valid insurance policy covering public liability. This obligation arises under S.O. 227(E) dated 24-03-1992 issued by the Ministry of Environment and Forests.
Public Liability Insurance Act, 1991 · S.O. 227(E) dated 24-03-1992

A word of counsel

The most common error on this tariff line is filing a bare bill of entry without the Chapter 28 additional qualifiers now mandated since 15 October 2023. Customs officers are instructed to verify qualifier completeness at assessment; a deficient declaration results in consignment detention and ground rent accumulation while the entry is returned for amendment. The public-liability insurance obligation is a separate, quantity-triggered requirement and must be assessed independently of the customs-declaration obligation.

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Frequently asked

Does HSN 2811 29 50 require BIS certification?

No, sulphur trioxide falls outside the BIS Quality Control Order regime; no BIS QCO covers this product family. Import is governed by CBIC mandatory-qualifier requirements under Chapter 28 and, where hazardous-quantity thresholds are crossed, by the Public Liability Insurance Act, 1991.

What are the mandatory additional qualifiers required under CBIC Circular 23/2023-Cus for Chapter 28 imports?

Paragraphs 4.1 and 4.2 of CBIC Circular 23/2023-Cus dated 30-09-2023 specify the qualifiers to be declared for commodities under Chapters 28, 29, 32, 39 and CTH 3808; the importer must ensure all stipulated fields are populated in the import declaration before filing.

When does the public-liability insurance obligation apply to a sulphur trioxide import?

The obligation under the Public Liability Insurance Act, 1991 and S.O. 227(E) dated 24-03-1992 is triggered when the imported quantity of the specified hazardous substance meets or exceeds the threshold quantities prescribed in that notification; quantities below the threshold do not attract the insurance requirement.

Last verified against gazette notifications: 2026-05-16. Source: CBIC / Indian Customs CUSDATA.