Can I use HSN codes on GST invoices to classify purchases for Scope 3?
Yes, as a classification aid. The HSN code tells you what was bought, such as flat-rolled steel, plastics or machinery, which points to the Scope 3 category and the material. It does not give you an emission factor. You still need the quantity and unit from the invoice and a factor chosen for that material.
What an HSN code tells you
GST invoices for business buyers must show at least four digits, or six digits for suppliers with turnover above ₹5 crore, so most B2B lines carry a usable code.
- The chapter (first two digits) gives the broad material: 39 plastics, 48 paper and paperboard, 72 iron and steel, 73 articles of iron or steel, 76 aluminium, 84 machinery.
- The heading (four digits) narrows it: 7208 is hot-rolled flat steel, 8457 is machining centres.
- SAC codes in chapter 99 cover services, such as 9965 for goods transport.
From code to category
- Materials and parts you consume, such as steel coil or plastic granules: Category 1, purchased goods.
- Machinery and equipment you capitalise (chapters 84 and 85 mostly): Category 2, capital goods. Confirm with your fixed asset register, because the same code can be a spare part you expense.
- Fuel (chapter 27) burned on site: Scope 1, not Scope 3. Electricity (2716): Scope 2.
- Freight services: Category 4 or 9, depending on who pays.
What HSN cannot do
There is no official mapping from HSN codes to emission factors. A code covers a product class, while emissions depend on how and where the item was made: steel from a blast furnace and steel from a scrap-based electric furnace share a code but differ widely. Pick the factor separately, from the supplier if possible, and record its source.
Traps to check
- Wrong or generic codes on small suppliers' invoices: read the description too.
- Units: steel by the tonne, cable by the metre, fasteners by the piece. The factor's unit must match.
- Mixed invoices: one invoice with several codes needs each line classified separately.
Worked example: one invoice line
- Line: HSN 7208, hot-rolled steel coil, 10 tonnes
- Category: 1, purchased goods; material: flat steel
- Factor (proxy, no supplier figure): about 1.9 t CO2 per t steel, worldsteel global average
- 10 x 1.9 = 19 t CO2, labelled as an average-data estimate
The HSN code chose the category and material; the factor came from a separate, named source.
What Senseible does here
Senseible classifies invoice lines by HSN or SAC code first, and by keyword only when the unit agrees. A line gets a figure only when its quantity and unit match an approved factor for that category and material; otherwise it shows Needs Data.
Sources: GHG Protocol Technical Guidance for Calculating Scope 3 Emissions (2013), Category 1, GHG Protocol Corporate Value Chain (Scope 3) Standard (2011), worldsteel sustainability indicators (CO2 intensity of steel)
Last reviewed 2026-10-15.