Westinghouse Saxby: the sole or principal use test and the end of easy classification

One judgment about railway brake blocks rearranged classification for every component maker in India.

The question

The assessee manufactured relays. Electrically, a relay is a relay, and Chapter 85 covers electrical apparatus for switching. Functionally, these relays were manufactured to a railway specification and were usable only in railway signalling equipment.

The revenue said Chapter 85, relying on the specific heading and on the exclusion in Note 2(f) to Section XVII, which excludes electrical machinery and equipment of Chapter 85 from parts of railway rolling stock.

The assessee said Chapter 86, relying on the sole or principal use test recognised in Note 3 to Section XVII and the line of authority which classified components by their dedication to a particular machine.

What the Court held

The Court accepted the assessee's classification. It reasoned that Note 3 to Section XVII, which requires parts to be classified with the machine for which they are solely or principally used, cannot be rendered otiose by the exclusion in Note 2(f).

It read the exclusion as applying to electrical machinery and equipment which retains an independent commercial identity, and not to an article manufactured to a railway specification with no other use.

The Court also relied on the predominant use of the product and on the absence of any market for the article outside railway signalling.

The decision was rendered under the Central Excise Tariff, but the Customs Tariff structure, the Section and Chapter Notes and the General Rules of Interpretation are the same instruments that govern GST classification, so the reasoning carries over.

How the judgment is being used, in both directions

Taxpayers use it where a dedicated component attracts a lower rate as a part of a machine or vehicle than as a generic article. Auto component makers, railway suppliers, defence suppliers and capital goods manufacturers have all pressed it.

The department uses it in reverse where classification as a part attracts a higher rate. Once the test is that the sole or principal use governs, it governs in whichever direction the rate moves. Practitioners who cite Westinghouse selectively find it cited back at them.

The battleground has therefore moved from tariff description to evidence of use. Drawings, specifications, approvals, customer certifications, absence of an alternative market, and the manufacturer's own catalogue now decide these cases.

Building a classification file that survives

Start with the General Rules of Interpretation and apply them in sequence. Rule 1, then the relevant Section and Chapter Notes, then Rule 3 for competing headings. An opinion that jumps to common parlance without exhausting the Notes is not an opinion, it is a preference.

Then the evidence of use. A technical specification issued by the customer, a drawing bearing a part number, a type approval, and a statement of the products in which the article can physically be fitted.

Then the market evidence. A catalogue, price list and sales analysis showing that the article is not sold for any other application.

Then the history. Classification adopted at import, in the pre GST regime, by competitors, and in any advance ruling. Consistency is persuasive; a change in classification without a change in the article invites the question why.

Authorities relied on

What to do on Monday

1. Prepare a classification file for each disputed article containing the tariff analysis in Rule sequence, the technical specification, the use evidence and the market evidence.

2. Test the sole or principal use argument in both directions before relying on it; if it raises your rate on another product, the department will find it.

3. Reconcile the HSN used in GSTR-1, in the invoice master, at import and in the pre GST regime; inconsistency is the first thing an auditor finds.

4. Where a product line is genuinely borderline and volumes are large, consider an advance ruling before scaling, not after.

Questions we are asked on this

Does Westinghouse apply to GST classification when it was an excise case?

Yes in method. GST rate notifications adopt the Customs Tariff headings and the Section and Chapter Notes, so the interpretive instruments are identical.

Our component fits our customer's machine and also a generic application. Are we covered?

Probably not on the sole use limb. You then argue principal use, which is a quantitative question. Be prepared to produce a sales analysis by application.

Can an advance ruling settle this for us?

It binds only the applicant and the officer concerned, for the transaction ruled on. It is useful for a new product line and useless as a general shield.

Is the department entitled to change classification for past periods?

It is, within limitation, but a change in classification without a change in the product or the tariff attracts the argument that no suppression can be alleged, which affects both the Section 74 invocation and the penalty.

What is the risk of reclassifying voluntarily?

A voluntary change draws attention to prior periods. Model the past exposure and the limitation position before you change a single HSN in the master.

In this cluster

• GST 2.0: two slabs did not end classification litigation, they moved the battle line
• Rate change transition: time of supply, credit notes and stock in hand
• Classification disputes under GST: the principles the courts apply
• HSN, common parlance and the General Rules of Interpretation
• Composite supply versus mixed supply: the test, and the tax
• Principal supply in bundled contracts: getting the rate right
• Food, beverages and the restaurant service rate maze
• Textiles and apparel: the rate structure and the disputes it produces
• Pharmaceuticals and medical devices: the concession and its boundaries
• Automobiles and auto components: the rate bands and the component question

GST Insights is published by AMLEGALS for general information. Law stated as on 3 September 2026. Not advice on any particular set of facts; not an advertisement or a solicitation under Rule 36 of the Bar Council of India Rules. Readers with a question on their own facts may write to the GST practice of their own accord.