# Can I use HSN codes on GST invoices to classify purchases for Scope 3?

Canonical: https://senseible.earth/answers/can-hsn-codes-be-used-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.

- [HSN code to emission factor mapping](https://senseible.earth/answers/hsn-code-emission-factor-mapping)
- [Footprint from invoices](https://senseible.earth/answers/how-to-calculate-carbon-footprint-from-invoices)
- [Scope 3 supplier evidence](https://senseible.earth/scope-3-supplier-evidence)

Sources: [GHG Protocol Technical Guidance for Calculating Scope 3 Emissions (2013), Category 1](https://ghgprotocol.org/standards), [GHG Protocol Corporate Value Chain (Scope 3) Standard (2011)](https://ghgprotocol.org/corporate-value-chain-scope-3-standard), [worldsteel sustainability indicators (CO2 intensity of steel)](https://worldsteel.org)

Last reviewed 2026-10-15.