Commercial sulfuric acid enters Indian tariff administration under HSN 2807 00 10, CAS 7664-93-9, a mineral acid with molecular mass 98.079 g/mol and a 98% grade density of 1.84 g/cm³ at 25 °C. In 2026 trade data, the search-pattern “Sulfuric Acid Import Duty into India 2026: Why Sources Disagree 14.31% vs 27.73%” is not an isolated contradiction; it results from the way Indian border taxes, welfare surcharges, and integrated goods and services tax are stacked on the same CIF value. The tariff line is governed by the Customs Tariff Act 1975, Schedule I, Section VI, Chapter 28, and the IGST is collected under Section 3(7) of the Customs Tariff Act 1975. Because sulfuric acid is imported both as merchant-grade acid and as oleum for sulfonation, alkylation, and spent-acid regeneration, the valuation point, end-use notification, and treatment of input tax credit produce materially different landed-duty expressions.

Why a Standard MFN Shipment Generates 27.73% Effective Duty

For a cargo of concentrated H₂SO₄ at 98% w/w, the reproducible arithmetic uses basic customs duty at 7.5% of CIF, social welfare surcharge at 10% of basic customs duty, and integrated GST at 18% on CIF plus basic customs duty plus social welfare surcharge. The formula is ((1 + 0.075 + 0.0075) × 1.18) − 1 = 27.735%, rounded to 27.73%. The IGST component alone is 19.485% of CIF. The lower reported value of 14.31% cannot be obtained by merely deleting IGST because the residual would be 8.25%; therefore 14.31% embodies a separate duty-like burden of 6.06% over the basic customs duty plus social welfare surcharge base.

The 14.31% Figure as a Partial Customs Charge or Trade-Weighted Average

Sources do not necessarily err when they quote 14.31%. The First Schedule of the Customs Tariff Act 1975 contains the basic customs duty; the social welfare surcharge is applied as a separate statutory charge; IGST is applied under Section 3(7) of the Customs Tariff Act 1975. A data source that calls “import duty” only the permanent customs levies and adds a specific anti-dumping or countervailing duty may land at 14.31% before IGST. Another source that uses the landed-cost definition—basic customs duty plus social welfare surcharge plus IGST—will report 27.73%. The difference is an analytical boundary, not a change in the product’s tariff classification.

The classification of sulfuric acid under HSN 2807 00 10 is generally stable, but anti-dumping measures are country-selective. Under Sections 9A and 9B of the Customs Tariff Act 1975, a definitive or provisional duty can be added to the basic customs duty and social welfare surcharge. When such a country-specific duty is 6.06% of CIF, the pre-IGST total is 14.31%. Because such duties are published in Directorate General of Trade Remedies notifications and customs databases do not always consolidate them, aggregator platforms may omit them. Published data for the specific 2026 anti-dumping status of every sulfuric acid trade partner is limited, and the importer must verify the notification in the e-Gazette and the ICEGATE bill of entry.

When Battery-Grade Sulfuric Acid Is Imported, Trace Metal Limits Determine Eligibility

Battery-grade H₂SO₄ is controlled under IS 266:1993 for total acidity, residue on ignition, iron, chloride, manganese, copper, arsenic, and nitrates. A typical specification is 98% w/w minimum acidity, with Fe below 50 mg/kg, Cl below 10 mg/kg, Mn below 2 mg/kg, and Cu below 1 mg/kg. Total acidity is determined by sodium hydroxide titration with ISO 910:1977 or ASTM E223-16. Trace-metal analysis uses ICP-OES after dilution; iron is also determined by thiocyanate spectrophotometry in some import inspection certificates. The density of the conforming material at 25 °C is approximately 1.84 g/cm³.

The electrolyte in lead-acid batteries is diluted to 37% w/w H₂SO₄ with density 1.285 g/cm³ at 25 °C. The imported material is typically concentrated acid that battery manufacturers dilute on-site in acid-resistant plastic circulation loops. Total acidity is the primary specification, but trace metals such as zinc, cobalt, and nickel are controlled because they promote gassing and self-discharge.

Merchant-grade acid imported for phosphatic fertilizer production is commonly delivered as 98.5% w/w virgin acid or oleum with free SO₃ between 20% and 65%. The oleum route is preferred in sulfonation of linear alkylbenzene and in nitration spent-acid regeneration. At discharge terminals in Kandla, Hazira, and JNPT, transfer pumps are specified with PTFE mechanical seals and ETFE-lined casings, while carbon-steel storage tanks operate with a corrosion allowance of 3 mm and a design specific gravity of 1.84. The vent systems use 5–10% w/w NaOH scrubbers. At ambient temperature, mild steel corrosion in 98% acid is often below 0.05 mm/year; at 60 °C, weld-zone rates can approach 0.5 mm/year, which makes tank pad temperature control a safety-relevant operating parameter.

Storage, Unloading, and Venting Requirements for Indian Port Receipts

Sulfuric acid is transported as UN 1830, Class 8, packing group II under the IMDG Code. Spent sulfuric acid is UN 1832; oleum is UN 1831. ISO tank containers for 98% acid are typically 25,000 L stainless-lined or carbon-steel units with PTFE gaskets and top discharge. The unloading rate is governed by the return air vent capacity and the scrubber blower rather than the pump curve; a 30 m³/h transfer through an 80 mm hose creates a frictional pressure drop that is lower than the static head of the storage tank, provided the acid temperature is below 40 °C. Viscosity at 25 °C for 96% acid is about 25.6 mPa·s, but it rises steeply below 0 °C; freeze protection is therefore required for tanks in northern Indian terminals.

Dilution of concentrated sulfuric acid must proceed acid-to-water under continuous agitation because the enthalpy of mixing at 50% w/w can exceed 80 °C if a single stream is fed without cooling. In compounding operations, the dilution vessel is often a PVDF-lined or glass-lined reactor with a heat-transfer jacket. The use of water-to-acid sequence creates localized boiling at the interface and can eject acid mist. The resulting mist is controlled by knitted PTFE demisters and 5% NaOH scrubbers, with stack emission opacity below 20% as a practical operating threshold.

What Documentation Converts a Tariff-Rate Query into an Import Duty Number?

The bill of entry filed in ICEGATE is the authoritative document for a specific consignment. It captures the transaction value under Section 14 of the Customs Act 1962, the Customs Valuation (Determination of Value of Imported Goods) Rules 2007 adjustments, the notification exemption number, the country of origin, the preferential rate, and the IGST rate. For a standard MFN shipment, the system computes basic customs duty, social welfare surcharge, and IGST separately; the resulting total is the source of the 27.73% figure. When a separate source quotes 14.31%, the basis should be checked for whether it is a rate average, an ad valorem equivalent, a partial pre-GST stack, or a product-specific anti-dumping notification. Without the notification number, the lower figure cannot be mapped to a specific legal instrument.

Importers using an Advance Authorization under the Foreign Trade Policy 2023 or a MOOWR license under Section 65 of the Customs Act 1962 can defer or exempt basic customs duty and IGST on sulfuric acid used for export production. Such scheme-specific treatment is another reason why trade journals may report a lower figure than the general tariff stack. The same quantity of acid imported under an advance authorization may attract no upfront duty, while an identical merchant shipment for domestic sale attracts the full MFN stack.

Before shipment, the Indian buyer often appoints a third-party inspection agency for tank cleaning verification and ullage measurement; the acid must be free of hydrocarbons, hydrogen sulfide, and suspended solids. A certificate of analysis with ISO 910:1977 total acidity and trace-metal limits is required for letter-of-credit negotiation. The operational incompatibility is with alkalis, amines, hypochlorite, and organic material; even small quantities of reducing organics can generate SO₂ in storage. Water contamination below 93% w/w accelerates carbon-steel corrosion; therefore import terminals reject parcels where the average concentration falls below 93% w/w.