Modern businesses rarely operate from a single location. As organisations expand, they establish project offices, branches, and operational units across several States or Union Territories. This is particularly common in sectors such as infrastructure, telecommunications, consulting, and financial services.
Consider Aayra Ltd., a large infrastructure company executing projects across multiple States. For administrative efficiency, the company procures several services centrally through its corporate office in Delhi, such as statutory audits, IT support, project consultancy, and insurance. Consequently, invoices for these services are issued to the Delhi office even though the benefits extend to project offices located in different States.
Since each State registration under GST is treated as a distinct person, an important question arises: how should the input tax credit of such common services be shared among the units that actually use them?The GST law addresses this through the Input Service Distributor (ISD) mechanism, which ensures that the credit of GST paid on common input services is distributed to the units that actually utilise them. The significance of this framework has increased following legislative changes that make ISD mandatory from 1 April 2025 for the distribution of credit for common input services.
The Conceptual Basis of the ISD Mechanism
The statutory provisions governing the Input Service Distributor (ISD) mechanism are primarily contained in Sections 2(61), 20 and 21 of the CGST Act, 2017, read with Rule 39 of the CGST Rules, 2017.Section 2(61) defines an Input Service Distributor as follows:
"Input Service Distributor" means an office of the supplier of goods or services or both which receives tax invoices towards the receipt of input services, including invoices in respect of services liable to tax under sub-section (3) or sub-section (4) of section 9 of this Act or under sub-section (3) or sub-section (4) of section 5 of the Integrated Goods and Services Tax Act, 2017 (13 of 2017), for or on behalf of distinct persons referred to in section 25, and is liable to distribute the input tax credit in respect of such invoices in the manner provided in section 20.
The need for this mechanism arises from a fundamental feature of GST. Under Section 25 of the CGST Act, registrations obtained by the same entity in different States are treated as distinct persons, even though they share the same PAN.Therefore, when one registered unit receives an invoice for input services, but the benefit extends to other units of the organisation, the credit cannot remain with the receiving unit alone. It must be distributed among the units that actually utilise those services.
The ISD mechanism serves as the statutory channel through which such credit is allocated among the organisation's registered units.
Section 20 - Statutory Framework for Distribution of Credit
Section 20 of the CGST Act provides the statutory foundation for the distribution of input tax credit by an Input Service Distributor (ISD).
Section 20(1) provides that any office of the supplier of goods or services or both which receives tax invoices towards the receipt of input services- including invoices in respect of services liable to tax under sub-section (3) or sub-section (4) of section 9 of the CGST Act or under sub-section (3) or sub-section (4) of section 5 of the Integrated Goods and Services Tax Act, 2017 (13 of 2017)- for or on behalf of distinct persons referred to in section 25, shall be required to be registered as an Input Service Distributor under clause (viii) of section 24 and shall distribute the input tax credit in respect of such invoices.
The purpose of this provision is to ensure that the credit ultimately flows to the units that actually utilise the services rather than remaining with the office that merely receives the invoice.
Section 20(2) provides that the Input Service Distributor shall distribute the credit of central tax or integrated tax charged on invoices received by it, including the credit of central or integrated tax in respect of services liable to tax under sub-section (3) or sub-section (4) of section 9, where such tax is paid by a distinct person registered in the same State as the said Input Service Distributor, in such manner, within such time, and subject to such restrictions and conditions as may be prescribed.
Accordingly, the credit must be distributed in the manner and within the time prescribed under the CGST Rules, 2017. The provision also enables the distribution of credit relating to services liable to tax under the Reverse Charge Mechanism under section 9(3) or section 9(4) of the CGST Act, 2017, as well as under section 5(3) or section 5(4) of the IGST Act, 2017.
The substituted Section 20(2) expands the operational scope of the ISD mechanism. Under the amended provision, the mechanism applies even where both the ISD and the recipient of credit are located within the same State.
This provision is particularly significant because it empowers the Government to prescribe detailed procedural rules governing the distribution of credit. Pursuant to this enabling authority, Rule 39 of the CGST Rules, 2017 has been framed to lay down the manner and conditions for such distribution.
Section 20(3) further provides that the credit of central tax shall be distributed as central tax or integrated tax, and the credit of integrated tax shall be distributed as integrated tax or central tax, by way of issue of a document containing the amount of input tax credit, in such manner as may be prescribed.Accordingly, the ISD is required to issue a prescribed document (commonly referred to as an ISD invoice) to distribute the credit. Through such a document, the credit of central tax may be distributed either as central tax or integrated tax, while the credit of integrated tax may be distributed either as integrated tax or central tax, in the manner prescribed under the CGST Rules.
Rule 39 - Procedure for Distribution of Input Tax Credit by Input Service Distributor
The procedural framework for the distribution of input tax credit by an ISD is prescribed in Rule 39 of the CGST Rules, 2017. The rule has undergone substantial substitution and expansion with effect from 1 April 2025, pursuant to Notification No. 12/2024–Central Tax dated 10 July 2024 read with Notification No. 09/2025–Central Tax dated 11 February 2025.
Rule 39 lays down the detailed operational mechanism through which an Input Service Distributor distributes credit received in respect of input services to the various units or distinct persons of the same organisation.
At the outset, Rule 39(1)(a) requires that the input tax credit available for distribution in a particular month be distributed within that same month. The constitutional validity of Rule 39(1)(a) recently came under scrutiny before the Madras High Court in Reliance Jio Infocomm Ltd. vs Union of India & Others- 2026-VIL-230-MAD dated 05 March 2026. The petitioner challenged the requirement that credit be distributed in the same month as the invoice was received.The High Court upheld the validity of Rule 39(1)(a) but clarified that the phrase " input tax credit available for distribution " refers to credit that becomes legally available after fulfilment of the statutory conditions under Section 16(2). Thus, credit does not become distributable merely upon receipt of an invoice; it becomes distributable only after the statutory conditions for entitlement are satisfied.
The details of such distribution are required to be furnished in Form GSTR-6, which is the statutory return prescribed for Input Service Distributors under Chapter VIII of the CGST Rules (Rules 59 to 84) dealing with returns.
An important safeguard in the rule is that the amount of credit distributed by the ISD cannot exceed the amount actually available for distribution. This ensures that the distribution mechanism operates strictly within the limits of credit legitimately received.
Rule 39 emphasises proper credit attribution. Where an input service is attributable to a specific recipient, the credit must be distributed only to that recipient. Where the service benefits multiple units, the credit must be distributed proportionately among those recipients.
Where input services benefit multiple units, the credit must be distributed pro rata based on the turnover of each recipient during the relevant period. Similarly, where the input service is attributable to all recipient units, the credit must be distributed among all operational recipients on the same turnover-based proportion.
The rule prescribes a formula to determine each recipient's share based on its turnover relative to the aggregate turnover of all recipients.
The ISD must distribute eligible and ineligible credit separately. Ineligible credit- such as credit blocked under Section 17(5) or otherwise restricted under the law- must be distinctly identified and distributed separately from eligible credit so that the recipients can appropriately account for such credit in their own records.
The rule also mandates separate distribution of different tax components, namely, central tax, State tax or Union territory tax, and integrated tax.
The integrated tax credit must be distributed as an integrated tax credit to all recipients. However, central tax and State/UT tax credits are distributed as central tax and State/UT tax, respectively, where the recipient is located in the same State as the ISD, and as integrated tax where the recipient is located in another State
For the purpose of distributing credit, the ISD is required to issue a prescribed document known as an ISD invoice, as provided under Rule 54(1) of the CGST Rules. This document must clearly indicate that it is issued solely for the distribution of input tax credit. Similarly, if the credit previously distributed requires a reduction for any reason, the ISD must issue an ISD credit note.
Where a debit note increases the credit available to the ISD, the additional credit must be distributed in the same manner in the month in which the debit note is reported in Form GSTR-6.
Where a credit note reduces the credit earlier distributed, the reduction must be apportioned among the recipients in the same ratio as the original distribution. If the adjustment results in a negative amount, it is added to the output tax liability of the concerned recipient.
A significant new insertion is Rule 39(1A), effective from 1 April 2025, which introduces an additional procedural mechanism for transferring the credit of certain common input services to the Input Service Distributor.It is important to note that an ISD is merely a mechanism for the distribution of input tax credit and is not itself required to discharge tax liability on services. Consequently, where tax on input services is required to be paid- particularly under the Reverse Charge Mechanism (RCM) - such tax is paid by a normal registered person having the same PAN and State code as the ISD.
Rule 39(1A) facilitates this arrangement. Under this provision, the registered person who has paid the tax may issue an invoice or credit/debit note to the ISD in accordance with Rule 54(1A ) for transferring the credit of such common input services to the ISD. Once the credit is transferred in this manner, the ISD distributes the credit to the respective distinct persons in accordance with Rule 39(1).
The rule also clarifies that, where the credit has already been distributed by the ISD and subsequently requires reduction- for example, where it has been distributed to the wrong recipient- the adjustment must be carried out in accordance with the prescribed procedure for reducing credit.Further, the ISD is required to issue the ISD invoice to the recipient entitled to such credit and report both the ISD invoice and any ISD credit notes in Form GSTR-6 for the relevant month.
Finally, the rule includes explanations of important terms, such as "relevant period,""recipient of credit," and "turnover," which are essential to the correct application of the turnover-based distribution formula.
Illustration 1 - Distribution of Common Services
Suppose Aayra Ltd. receives a consultancy invoice of Rs 10,00,000 plus GST at its Delhi office. The consultancy services relate to project offices located in Delhi, Haryana and Punjab.The turnover of these project offices during the relevant financial year is Rs 60 crore, Rs 30 crore and Rs 10 crore respectively. Accordingly, the credit will be distributed in the ratio 60:30:10 among the Delhi, Haryana, and Punjab project offices.Thus, the credit reaches the units that actually benefit from the services.
Illustration 2 - Reverse Charge Services
Consider another situation in which Aayra Ltd. receives sponsorship services from an unregistered supplier liable to tax under the Reverse Charge Mechanism. In such cases, the regular GST registration in the same State as the ISD must first discharge the tax liability under the RCM. The ISD then distributes the credit among the recipient units.
Section 21 - Recovery of Excess Credit Distributed by ISD
Section 21 deals with situations where an Input Service Distributor distributes input tax credit in excess of what is actually available or permissible to one or more recipients. In such cases, the excess credit must be recovered from the recipients to whom it was erroneously distributed.
The recovery of such excess credit is carried out in accordance with the statutory provisions governing the determination of tax under the GST law. Accordingly, proceedings for recovery may be initiated under Section 73, Section 74, or Section 74A of the CGST Act, depending upon the nature of the case.
Thus, while the ISD mechanism facilitates the smooth distribution of credit within an organisation, any excess or erroneous credit remains recoverable from the concerned recipients.
Before concluding, it may be clarified that the clause numbers of the various sub-clauses of Rule 39(1) and the mathematical formula prescribed for ISD distribution have deliberately not been reproduced in this article . While these provisions form the statutory framework of the ISD mechanism, the objective here has been to emphasise conceptual understanding rather than computational mechanics. Accordingly, the substance and operational principles of Rule 39(1) have been discussed so that the focus remains on the core idea - "one invoice, many units.
A Reflection on the Philosophy of the ISD Mechanism
The ISD mechanism reflects the destination-based principle of GST. Services may be procured centrally, yet their benefits extend across multiple operational units. The ISD framework ensures that the input tax credit ultimately flows to the units that actually utilise those services.
Seen from this perspective, the ISD mechanism is not merely a procedural requirement but a structural element of the GST framework that ensures equitable distribution of input tax credit across an organisation.Perhaps the idea can be expressed in simple terms:
Just as responsibility ultimately rests where work is performed, the tax credit, too, must ultimately reach the place where value is created.
By: CA Raj Jaggi & Adv Kirti Jaggi
CAclubindia
