Input Service Distributor (ISD) is the GST mechanism for distributing input tax credit on common input services from one office of a business to other units having the same PAN. It is especially relevant for groups where a head office receives invoices for services such as audit, software, consulting, advertising or professional support that benefit multiple GST registrations.
CBIC's official GST FAQ on Input Service Distributor describes an ISD as an office that receives tax invoices for input services and distributes the related CGST, SGST/UTGST or IGST credit to suppliers having the same PAN. The GST Portal's GSTR-6 manual shows how the ISD receives invoice details and reports the credit distributed to recipient units.
When is an ISD useful?
Consider a company with registrations in Delhi, Maharashtra and Karnataka. Its Delhi head office receives one annual software invoice covering users across all three locations. If the invoice relates to services used by multiple registrations, the ISD framework provides a structured way to distribute the eligible input tax credit to the units to which the service is attributable instead of leaving all of the credit at the office that happened to receive the vendor invoice.
The mechanism is for input services. It should not be treated as a general device for shifting any unused GST credit between registrations. Credits relating to goods, capital goods or locally procured items need to be analysed under the normal GST provisions rather than pushed through ISD merely because another unit could use the credit.
Does an ISD need a separate GST registration?
Yes. CBIC's GST FAQ states that an ISD requires a separate registration and that the normal registration threshold does not apply to the ISD registration. The CGST Act also lists an Input Service Distributor among persons required to register irrespective of the ordinary turnover threshold. A business should therefore distinguish its ISD GSTIN from the regular GST registration through which the same office may make taxable outward supplies.
How does credit distribution work conceptually?
The core principle is attribution. Credit relating entirely to one recipient unit should follow that recipient. Credit relating to more than one recipient should be distributed among the relevant recipients in the manner prescribed under the GST law rather than allocated arbitrarily. The recipient units must have the same PAN as the ISD.
For finance teams, this means the allocation basis should be supported before GSTR-6 is prepared. A monthly working can identify each common-service invoice, the units benefited, eligibility of the credit and the amount to be distributed. The ISD document and return should then follow that working.
What is Form GSTR-6?
GSTR-6 is the return for an Input Service Distributor. The GST Portal manual states that it contains details of input tax credit received for distribution, amendments and credit/debit notes, as well as the distribution or redistribution of eligible and ineligible ITC through ISD invoices and ISD credit notes.
The portal manual currently states that GSTR-6 is due on the 13th of the succeeding month unless the due date is extended. Because statutory due dates can be changed for particular periods, businesses should still verify the live GST portal and applicable notifications for the filing month rather than relying permanently on a calendar embedded in an old SOP.
What does the recipient see?
Once the ISD reports distributed credit through GSTR-6, the information flows into the GST system for the recipient registration. The receiving unit should reconcile ISD credit with its GST records instead of booking a manual inter-branch credit unsupported by the ISD return.
A useful control is to maintain a month-wise reconciliation between the ISD's distributed amount and the amounts appearing for each recipient GSTIN. Differences should be investigated for wrong GSTINs, incorrect tax heads, credit notes, amendments or timing mismatches.
Practical example
Assume ABC Ltd has three GST registrations under one PAN. Its head office receives a ₹3,00,000 plus GST invoice for a cloud platform used by all three units. The invoice is addressed to the office operating as the ISD and the underlying service is eligible for ITC. The finance team first determines which units actually use the platform and applies the prescribed distribution basis to the relevant recipients. It then issues the appropriate ISD documents and reports the distribution in GSTR-6.
If a separate legal-service invoice relates only to one of the three units, that credit should not automatically be spread across all three simply because the invoice reached head office. The attribution should follow the unit to which the service relates, subject to the statutory distribution rules and ITC eligibility conditions.
ISD versus cross-charge
ISD and cross-charge solve different GST questions. ISD is a mechanism for distributing credit of common input services received by an office. Cross-charge generally concerns a supply made by one distinct person or registration to another, such as internally supplied services that require analysis as a taxable supply between registrations.
A business should therefore avoid using “ISD or cross-charge” as a purely tax-optimisation choice. Start by identifying the underlying transaction: is the office distributing third-party input-service credit, or is one registered unit itself supplying a service to another distinct person? The accounting documentation and GST treatment should follow that factual distinction.
Monthly ISD compliance checklist
- Capture common-service invoices: identify invoices received by the ISD and verify supplier GSTIN, invoice number, date, place of supply and tax amounts.
- Test ITC eligibility: separate eligible and ineligible credit before distribution.
- Identify recipient units: document which same-PAN GST registrations actually relate to the service.
- Apply the prescribed distribution basis: do not allocate credit merely to exhaust the ISD ledger.
- Account for credit and debit notes: link subsequent vendor adjustments to the original allocation logic and report them correctly.
- Prepare ISD invoices or credit notes: ensure document numbers and recipient GSTINs are controlled and traceable.
- File GSTR-6: reconcile the return to the invoice register and distribution working before filing.
- Reconcile recipient credits: confirm that each unit's GST records reflect the distributed amounts and investigate exceptions.
Common mistakes to avoid
- Using ISD to distribute credit relating to goods or capital goods without analysing whether the mechanism legally applies.
- Operating only under the head office's normal GSTIN and overlooking the separate ISD registration requirement.
- Distributing a service to every GST registration even when it is attributable only to selected units.
- Ignoring ineligible ITC while preparing the distribution working.
- Failing to process vendor credit notes and later adjustments through the ISD reconciliation.
- Confusing third-party input-service credit distribution with a taxable cross-charge between distinct persons.
Practical takeaway
ISD works best when it is treated as a controlled monthly allocation process rather than a year-end credit-transfer exercise. Identify common input-service invoices, establish which same-PAN units benefited, test ITC eligibility, apply the prescribed distribution rules, report the documents in GSTR-6 and reconcile the recipient GSTINs. The most important first question is whether the transaction is genuinely distribution of third-party input-service credit; if it is an internal supply between registrations, a separate cross-charge analysis may be required.
