Input Service Distributor (ISD) Under GST — Registration, ITC Distribution and GSTR-6

Any business with one GST registration handling input services on behalf of other registrations under the same PAN — a head office paying for a group insurance policy, a shared audit fee, or a common software licence used across branches in different States — runs into the same question eventually: how does the Input Tax Credit on that shared expense get to the branches that actually need it? The answer, under GST, is the Input Service Distributor (ISD) mechanism.

An ISD, defined under Section 2(61) of the CGST Act, is an office of a supplier that receives tax invoices for input services and distributes the credit on those invoices to other registrations of the same PAN — never to credit on goods or capital goods, only on services. Registration as an ISD is separate from a regular GST registration (Form GST REG-1, with the ISD option specifically ticked) and does not, by itself, let that office make outward supplies; its sole function is receiving and redistributing input-service credit.

Distribution itself follows Rule 39 of the CGST Rules and runs on a strict pro-rata formula: credit attributable to a specific recipient unit goes entirely to that unit, while credit that benefits multiple units is distributed in the ratio of each unit’s turnover in the relevant period to the aggregate turnover of all units to which the service is attributable. The ISD issues an ISD invoice or ISD credit note (Rule 54) to pass the credit on, and reports the entire exercise monthly in Form GSTR-6 — a return with no “nil” exception; it must be filed even in a month with nothing to distribute.

Sidebar: a common point of confusion worth clearing up directly — ISD registration became mandatory, not optional, for any entity distributing common input-service credit across distinct GST registrations under the same PAN, effective from 1 April 2025 (per the GST Council’s earlier recommendations giving effect to this change). A business still routing shared input-service credit through an internal cross-charge mechanism instead of formal ISD registration and GSTR-6 reporting is, as of this financial year, operating outside the compliant route, not merely using an alternative one.

Why It Matters

ISD compliance sits in the gap between “obviously required” and “easy to overlook” — many groups with shared head-office expenses have been informally cross-charging for years without ever registering as an ISD, and with the mechanism now mandatory rather than optional, that informal practice carries real exposure: disallowed credit at the recipient unit, and a missed monthly GSTR-6 filing obligation at the ISD office, going back to whenever the common-credit situation actually began.

Key Takeaways

• An ISD distributes credit only on input services, never on goods or capital goods (Section 2(61), CGST Act).
• Distribution to multiple benefiting units follows a strict turnover-ratio formula under Rule 39, CGST Rules — not management discretion.
• GSTR-6 is a mandatory monthly filing for a registered ISD, with no nil-return exemption.
• ISD registration is mandatory (not optional) for distributing common input-service credit across distinct registrations under the same PAN, effective 1 April 2025.
• An internal cross-charge arrangement used in place of formal ISD registration and GSTR-6 reporting is no longer a compliant substitute under the current framework.

Practical Implications

For any client group with more than one GST registration under the same PAN and any shared input-service expense — insurance, audit fees, common software, head-office rent recharges — confirm whether ISD registration has actually been obtained, rather than assuming an existing cross-charge practice is sufficient. Where it hasn’t, this is worth raising proactively rather than waiting for it to surface in an audit or departmental scrutiny, given the mandatory-registration change took effect over a year ago now. This also feeds directly into this year’s annual-return reconciliation — see Finoscape’s companion coverage of this cycle’s GSTR-9/GSTR-9C filing for FY 2025-26.

Action Checklist

• For any group-structure client, map every shared input-service expense currently being cross-charged informally and confirm whether formal ISD registration exists for the office incurring it.
• Where ISD registration is missing but required, raise remediation (registration, retrospective GSTR-6 catch-up as applicable, and correcting any resulting credit position) as a distinct compliance item, not folded into a general GST health check.
• For clients already ISD-registered, spot-check that the Rule 39 turnover-ratio distribution is being applied correctly across all benefiting units, not simplified informally.
• Confirm GSTR-6 has been filed for every month since ISD registration, including months with nothing to distribute.

Relevant Sections / Notifications

Section 2(61), CGST Act, 2017 (definition of Input Service Distributor). Section 20, CGST Act, 2017 (manner of distribution of credit by ISD). Rule 39, CGST Rules, 2017 (procedure for distribution of credit by ISD). Rule 54, CGST Rules, 2017 (ISD invoice / credit note). Form GSTR-6 (monthly ISD return).

FAQs

Q: Can an ISD distribute credit on goods or capital goods, not just services?
A: No. The ISD mechanism under Section 2(61) and Section 20 of the CGST Act applies only to input services. Credit on goods or capital goods is not distributed through the ISD route.

Q: Is ISD registration optional if a group already cross-charges shared expenses internally?
A: Not any more. ISD registration became mandatory, rather than optional, for distributing common input-service credit across distinct GST registrations under the same PAN, effective 1 April 2025 — an informal cross-charge arrangement alone is no longer treated as a compliant substitute.

This article is intended for general informational purposes only and does not constitute legal or tax advice. Readers should consult a qualified Chartered Accountant for guidance on their own group’s ISD registration and credit-distribution position. Prepared by Finoscape Editorial Team — hello@finoscape.com.