Input Service Distributor (ISD) Under GST

A head office pays for a statutory audit, a group-wide software licence, or a national advertising campaign, and the invoice lands on one GSTIN while the benefit is used by branches registered under several others. Before this was formalised, businesses handled that gap in different ways, some of them not defensible on audit. From 1 April 2025, the law settled the question: an Input Service Distributor registration is mandatory wherever this pattern exists, and the credit has to move through it in a prescribed way, on a monthly return. This post covers what ISD is, why it changed, how it differs from cross-charge, and what the distribution and filing cycle actually requires.

What an Input Service Distributor is

An Input Service Distributor is an office of a taxable person that receives tax invoices for input services and issues its own invoices — ISD invoices — to distribute the input tax credit on those services to other GSTINs of the same PAN that use them. It is defined for this purpose in Section 2(61) of the CGST Act.

The pattern it exists for is common in any multi-state business. Head office in one state contracts a single audit firm, a single enterprise software vendor, or a single advertising agency, and the resulting invoice covers work that benefits branches registered in several states. Those branches are, under GST, distinct persons even though they share a PAN — the concept is explained in multiple GST registrations under the same PAN. An ISD is the formal channel for moving credit between them.

An ISD does not supply anything and is not itself liable to pay output tax on the services it distributes. Its only function is administrative: receive the invoice, work out who benefits and by how much, and pass the credit on.

Why ISD became mandatory from April 2025

ISD registration existed in the law well before 2025, but it was optional. A business with common input services could choose ISD, or it could choose cross-charge, or in practice some businesses did neither and simply claimed the full credit at the head office GSTIN — a position that did not withstand scrutiny once an officer looked at where the service was actually consumed.

The Finance Act 2024 closed that choice for one specific case. It amended the definition in Section 2(61) and rewrote Section 20 so that ISD registration is mandatory, with effect from 1 April 2025, for distributing input tax credit on common input services procured from a third party — including services on which tax is paid under reverse charge — where those services are for or attributable to distinct persons registered under the same PAN. Read the mechanics of reverse charge itself in the reverse charge mechanism under GST.

The scope of the mandate is narrow and worth being precise about: it applies to common input services received centrally and meant for distinct persons. It does not turn every multi-GSTIN business into an ISD, and it says nothing about goods.

ISD versus cross-charge

The two mechanisms are frequently confused because they both move value between GSTINs of the same PAN, but they answer different questions and neither substitutes for the other.

In practice most multi-state businesses need both: ISD for the vendor invoices that land centrally, and cross-charge for the value the head office genuinely creates internally, such as a shared services team. Treating one as a workaround for the other is the mistake that draws scrutiny.

How credit is distributed

Rule 39 of the CGST Rules sets the distribution formula. Credit attributable to a single recipient unit — a service that only benefits one branch — is distributed entirely to that unit. Credit attributable to more than one recipient unit is distributed among them in the ratio of each unit's turnover in the state or Union Territory concerned, during the relevant period, to the aggregate turnover of all the units to which that credit is attributable.

Ineligible credit — for example credit blocked under Section 17(5) — is identified and distributed separately as ineligible, so it does not inflate what a recipient unit can actually claim in its input tax credit computation. Integrated, central and state tax are each distributed as the same head of tax where the ISD and the recipient are in the same state, and as integrated tax where they are in different states.

Registration and the monthly return cycle

An ISD registration is a separate GSTIN, obtained specifically for this purpose — it is not an add-on to the head office's regular registration and does not carry the head office's regular filing obligations. The ISD:

• Receives the vendor's tax invoice and records the input tax credit on it.
• Determines which recipient units the service benefits, and applies the Rule 39 turnover ratio.
• Issues an ISD invoice to each recipient unit for its share of the credit.
• Files GSTR-6 for the month, by the 13th of the following month, reporting the credit received and distributed.

The recipient units do not file anything specific to receive this credit. It appears in each unit's GSTR-2A as it is filed and, on the recipient side, the ISD's counterparty data is reflected in the recipient's GSTR-6A, an auto-drafted statement generated from the ISD's filing. The credit then flows into the recipient's GSTR-2B for the relevant period, the same statement that governs eligibility for ordinary purchase credit — see the full list of GST returns for where GSTR-6 and GSTR-6A sit relative to the others.

Who actually needs an ISD registration

The clearest signal is a vendor invoice addressed to one GSTIN for a service consumed across several. The businesses that run into this most often are multi-state operations with:

• A head-office-negotiated statutory or internal audit engagement covering all branches.
• An enterprise software or SaaS licence purchased once and used by every registered office.
• A national advertising or marketing contract that promotes the business as a whole, not one branch.
• Group insurance, legal retainers, or consulting engagements billed to head office.

A single-registration business, or a business where every vendor already invoices the specific GSTIN that consumes the service, has no common credit to distribute and no ISD requirement. Whether your business needs multiple registrations in the first place is a separate question covered in multiple GST registrations under the same PAN, and where GSTIN structure interacts with place of supply, see the place of supply rules.

Getting registered as an ISD

ISD registration is applied for through the standard REG-01 registration form, using the option to register specifically as an Input Service Distributor rather than as a regular taxable person. It follows the same portal process as any other GST registration — see the GST registration process for the document and verification steps — with the distinguishing choice being the registration category selected on the form.

Because an ISD is a distinct GSTIN, every GSTIN in the group, including the new ISD registration and each recipient unit, needs to be verified and tracked correctly before credit distribution starts — a transposed digit or a lapsed registration in the chain breaks the GSTR-6 filing and the recipient's GSTR-2B alike. Our API returns registration details and GSTR filing history for a GSTIN in one call, which is useful for confirming each entity in a multi-GSTIN group is active and current before you build a distribution workflow around it. Full pricing is at pricing.

Frequently asked questions