A chemical manufacturer's GST invoice must classify each product by its chemical identity, because rates differ sharply. Sulphuric acid (2807) and nitric acid (2808) are taxed at 5% from 22 September 2025, most other inorganic chemicals of chapter 28 and chemical preparations of 3824 at 18%. The bill should show the batch number, purity or concentration, packing type, net weight, and hazard class or UN number for transport, since buyers and transporters both rely on these details.
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Extra fields a chemical manufacturer invoice needs
Batch number and manufacturing date
Chemical buyers trace quality problems by batch. A batch number on each line links the invoice to the certificate of analysis and the retained sample.
Purity or concentration
State assay, such as 98% sulphuric acid or 48% caustic lye. Price depends on concentration, and customers verify it on receipt.
Packing and net weight
Mention drums, carboys, IBC tanks or tanker loads with net weight. Returnable containers should be listed separately so they are not mistaken for sold goods.
Hazard class and UN number
Many chemicals are dangerous goods. Showing the UN number and hazard class helps the transporter carry the load lawfully and matches the safety documents.
Certificate of analysis reference
Give the CoA number issued for the batch. Pharmaceutical and food-grade buyers will not unload without it.
Tanker or vehicle details
Bulk liquid chemicals move by tanker. Record the vehicle number and seal number, which also feed the e-way bill.
Standard GST invoice fields
Rule 46 of the CGST Rules applies to every tax invoice, including this one:
✓Supplier name, address and GSTIN
✓Consecutive invoice number (max 16 characters, unique for the year)
Notification 9/2025-Central Tax (Rate) names sulphuric acid (2807), nitric acid (2808) and fertilizer-grade phosphoric acid (2809) in the 5% schedule, while its 18% schedule covers all inorganic chemicals of chapter 28 not specified elsewhere, which includes caustic soda under 2815. A plant that makes sulphuric acid and also sells caustic lye cannot use one rate for its product range. Check each product against the notification rather than relying on the chapter number alone.
Specification-dependent classification
The same molecule can fall under different headings depending on form and use. A pure chemical compound belongs in chapter 28 or 29, but a mixture prepared for a specific use, such as a cleaning blend or a foundry binder, usually falls under chapter 34 or 38. Describe the product precisely on the invoice: a trade name alone does not support the classification if an officer questions it.
Returnable drums, carboys and IBCs
Containers that the buyer must return are not sold. Show them separately as returnable, with deposit amounts if any, and track their return. If containers are not returned within the agreed period and you charge the buyer for them, raise a proper tax invoice for the container at its own rate at that time.
E-way bills and e-invoicing
Chemical consignments, especially tanker loads, are usually far above ₹50,000 in value and need an e-way bill before movement. Most chemical units also cross the ₹5 crore aggregate turnover threshold for e-invoicing, so B2B invoices must carry the IRN and QR code from the Invoice Registration Portal. An invoice without IRN when e-invoicing applies is not a valid invoice for the buyer's credit.
Samples, trial lots and toll processing
Chemical makers often send free samples or trial drums to prospective buyers. A free sample sent to an unrelated party is generally not a supply for consideration, but it should still move on a delivery challan, and input tax credit on goods given away as free samples is blocked under section 17(5). Where you process a customer's own material for a fee, which the trade calls toll manufacturing, the customer's material arrives and leaves on challans and your invoice covers only the processing charge as a job-work service. Keep the customer's material, your own production and samples in separate stock records so the invoices and challans can be reconciled at audit.
Common billing mistakes
✕Charging 18% on all acids by habit, though sulphuric and nitric acid are named at 5% in the new notification.
✕Using a brand or trade name as the only description, leaving the chemical identity and HSN unclear.
✕Billing returnable drums and IBCs as sold goods, or failing to invoice them when they are not returned.
✕Dispatching tankers without the hazard class and UN number matching the product on the invoice.
Chemical manufacturer GST invoice: FAQ
What is the GST rate on sulphuric acid after the 2025 rate change?
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Sulphuric acid under heading 2807 is listed in the 5% schedule of Notification 9/2025-Central Tax (Rate), effective 22 September 2025. Nitric acid under 2808 is also at 5%.
Is caustic soda taxed at 5% or 18%?
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Caustic soda under heading 2815 falls under the general entry for inorganic chemicals of chapter 28 in the 18% schedule, as it is not specifically named in the 5% schedule.
Should a chemical invoice include the batch number?
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GST law does not require it, but almost every industrial buyer does. Batch numbers link the invoice to the certificate of analysis and are needed for quality complaints and returns.
How do I bill freight on tanker deliveries?
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When the supplier arranges delivery as part of the sale, freight is part of the value of the goods and is taxed at the product's rate. Show freight as a separate line on the same invoice rather than an untaxed extra.
Can a chemical manufacturer use the composition scheme?
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Only if aggregate turnover is within the composition limit and no inter-state outward supplies are made. Most chemical units sell across states and to buyers who need input tax credit, so composition rarely suits them.