One Taxpayer, One Set of Facts: How Section 6(2)(b) Became GST's Anti-Duplicate Proceedings Shield

Dual GST was designed as "one nation, one tax"… but for years many taxpayers lived a different reality: one nation, two departments, three wings, and four summons-often for the same period and the same issue.

That "parallel track" problem wasn't just annoying; it was structurally risky. If Central and State authorities (or even different wings within the same setup) chase the same dispute independently, you invite:

Section 6(2)(b) of the CGST Act (mirrored in most State GST laws) was meant to stop that. And in 2025, the law finally got a "rulebook" that officers and taxpayers can't ignore, thanks to Supreme Court of India.

The design: why Section 6 exists at all

GST runs on a single interface principle: a taxpayer is typically assigned to either the Central or State administration for routine functions like scrutiny/audit/assessment-so the taxpayer doesn't face two masters for the same compliance lifecycle. That's why the ecosystem talks about "cross-empowerment" (officers of one side can act under the other law in defined ways) and "administrative assignment."

At the same time, the system also accepts a practical reality: intelligence-based enforcement can't be boxed into administrative assignment. If a fake ITC chain spans multiple jurisdictions, the enforcement agency that first detects it must be able to act across the chain-but without creating a second, overlapping track. CBIC's clarifications (including the well-known D.O. letter dated 05.10.2018) reinforced this balance: enforcement action can be initiated across the taxpayer base, and the initiating authority can carry it to its logical conclusion.

So GST needed a traffic rule: coordinate powers, but don't duplicate adjudication.

That traffic rule is Section 6(2)(b).

What Section 6(2)(b) actually blocks (and what it doesn't)

The phrase that matters is: no proceedings shall be initiated on the same subject matter once a proper officer under the other GST law has already initiated proceedings.

Two words decide everything:

1) "Proceedings"

Is a summons a "proceeding"? Is a search a "proceeding"? Or does "proceedings" mean the formal adjudicatory track like SCN → reply → order?

2) "Same subject matter"

Does "same subject matter" mean "same financial year"? Or "same taxpayer"? Or does it mean "same cause of action / same liability being sought"?

For years, High Courts wrestled with these questions. Then the Supreme Court stepped in and standardised the playbook.

The turning point: the Supreme Court's 2025 framework

In M/S Armour Security (India) Ltd. v. Commissioner, CGST [2025(08)LCX0079], the Supreme Court didn't just decide the dispute-it laid down a structured interpretation and practical guidelines to prevent parallel proceedings.

The Supreme Court's key takeaways (in plain English)

A. Section 6(2)(b) is a bar on duplicative adjudication, not on basic fact-finding. The Court held that "initiation of proceedings" refers to formal adjudicatory commencement-typically by issuance of a show-cause notice. Summons, search, seizure and evidence-gathering steps are not, by themselves, "proceedings" for triggering the bar.

B. Intelligence enforcement can start from either side, but the other side shouldn't run a parallel track on the same issue.

The Court recognised the reality of intelligence-based cases: either Central or State may initiate, even if the taxpayer is administratively assigned to the other. But once one authority is seized of the same subject matter, the other should not start overlapping proceedings.

C. "Subject matter" is not the taxpayer or the year-it's the liability/contravention being pursued.

The Court linked "subject matter" to the particular tax liability/deficiency/obligation arising from a specific contravention. In fact, it accepted the "cause of action" style approach that many High Courts had taken.

D. A two-fold test for "same subject matter."

To decide overlap, the Court suggested a practical test:

1. Is the authority already proceeding on an identical liability/offence on the same facts?

2. Is the demand/relief identical (or partially overlapping)?

If yes, Section 6(2)(b) bites-and the later overlapping SCN should be quashed.

E. Practical guidelines: comply first, then flag overlap. The Court's guidance is very operational:

This is the Supreme Court's "anti-duplication protocol"-and it's now the central reference point.

How Section 6(2)(b) stopped duplicates: the case-law trail that built the doctrine

Below are high-impact case patterns showing how courts used Section 6(2)(b) (and its State equivalents) to prevent multiple tracks.

1) "Two SCNs for overlapping period/issue? The later one dies."

A clean example is the Calcutta High Court ruling in Baazar Style Retail Limited [2024(08)LCX0482], where the State SCN/order was set aside because the Central authorities had already initiated proceedings covering overlapping subject matter/period; the Court invoked Section 6(2)(b) of the State Act and quashed the later composite action (SCN + order + DRC-07).

Practical punchline: If you already have an SCN on a defined issue, a second authority can't run a second SCN on the same liability merely because it's "their turf."

2) "Three wings, one taxpayer, one period: stop parallel wings."

Even within the same ecosystem, duplication happens when audit, anti-evasion, and range formations move simultaneously.

In the Calcutta High Court's intra-court decision involving R. P. Buildcon (P) Ltd. [2022(09)LCX0107], the Court restrained other wings from proceeding further for the same period while audit proceedings were to reach their logical end-calling out the absurdity of parallel action "in the present days of electronic communications."

Practical punchline: Section 6(2)(b)'s logic isn't limited to Centre vs State; courts also frown on internal parallelism on the same period/issue.

3) "Summons ≠ proceedings" (so you can't dodge summons using 6(2)(b))

Many taxpayers tried a common defence: "State is already looking into me-so Central can't even summon me."

High Courts consistently pushed back: summons is part of inquiry; the bar comes later. The Supreme Court endorsed this approach squarely in Armour Security.

One often-cited illustration is Kuppan Gounder P.G. Natarajan (2021(09)LCX0036), which treated Section 70 summons as inquiry and held the Section 6(2)(b) bar activates when proceedings on the same subject matter are initiated (i.e., adjudicatory track), not at the summons stage. This line of thinking is explicitly discussed and approved in the Supreme Court judgment.

Practical punchline: You generally must comply with summons, but you can still prevent duplicate SCNs/orders later.

4) "Who started first?" matters when both are probing the same chain

Where State and Central both begin probing the same fake ITC chain, courts have often leaned towards: the first mover continues; the other should coordinate or step back.

This is visible in the discussion around Vivek Narsaria (2024(01)LCX0545), where the idea of "prior in point of time" and inter-related proceedings was used to hold that parallel tracks should not run; the compilation also notes reliance on Section 6(2)(b) read with the 05.10.2018 clarification.

Practical punchline: If you can show who commenced first on the same subject matter, you have a strong coordination argument.

5) "Not every overlap is illegal" - distinct infractions can coexist

Courts have also clarified that Section 6(2)(b) is not a blanket immunity. If the "subject matter" is genuinely different-distinct contraventions, different cause of action-parallel action may be permissible.

The Supreme Court expressly captured this nuance: if proceedings concern distinct infractions, the bar won't apply even if the liability looks similar.

A commonly discussed example is Satyam Castings Pvt. Ltd. (2024(04)LCX0299), where the Court treated "subject matter" as cause of action and analysed whether the DGGI's action was truly overlapping or based on a distinct contravention/value chain.

Practical punchline: Your best argument is not "two authorities exist," but "two authorities are chasing the same liability on the same facts."

6) "Transfer" is not automatic; law doesn't create a free-floating power to shift files

Taxpayers often hear: "State is doing it, but we are transferring to DGGI," or vice-versa.

In Stalwart Alloys India Pvt. Ltd. (2024(08)LCX0096), courts examined the structure and questioned transfer without express statutory backing-while reiterating the anti-parallelism principle rooted in Section 6(2)(b).

Practical punchline: Coordination is expected, but "transfer" must stand on a legal footing; it can't be a casual administrative shortcut.

The taxpayer's playbook after Armour Security (useful, practical, and court-approved)

If you're writing this for practitioners and businesses, this is the "do this on Day 1" section.

Step 1: Build a "Proceedings Map"

Maintain a simple file that records:

This becomes your evidence of overlap.

Step 2: Don't ignore summons-comply, then flag overlap

The Supreme Court is clear: summons alone may not disclose the full "subject matter," and the taxpayer should comply first.

But while complying, place a written intimation:

Step 3: The moment an SCN arrives-run the "two-fold test"

Ask:

1. Is the SCN targeting an identical or overlapping liability on the same facts?

2. Is the demand/relief identical or partly overlapping?

If yes, Section 6(2)(b) objection should be raised at the earliest, and you can rely directly on the Supreme Court's statement that overlapping SCNs "shall be quashed."

Step 4: Force inter-departmental communication (politely, in writing)

Armour Security expects authorities to coordinate and verify overlap inter-se once informed. A well-drafted representation can push this process without sounding confrontational.

Step 5: If duplication persists, writ remedy is expressly contemplated

The Supreme Court explicitly kept the door open: if authorities don't comply with the anti-duplication guidelines, the taxpayer may approach the High Court under Article 226.

Why Section 6(2)(b) matters beyond "taxpayer relief"

Section 6(2)(b) is not merely a defence tool; it's a governance mechanism:

That is precisely why the Supreme Court read Section 6 broadly and purposively-to "insulate taxpayers" from multiple jurisdictions for the same dispute while still allowing effective intelligence enforcement.

Suggested "catchy sub-headlines" you can use inside the article (optional)

Closing note

Section 6(2)(b) didn't magically eliminate duplicate proceedings on Day 1 of GST-but it provided the statutory spine, and the Supreme Court's 2025 decision finally supplied the operating manual: what counts as proceedings, what subject matter means, and exactly how overlapping actions should be handled.

Disclaimer: The information given in this article is solely for purpose of understanding the law. It is completely based on the interpretation of the author and cannot be constituted as a legal advise, the author of this article and Lawcrux team is not responsible for any legal issues if arises on the basis of the interpretation given above.