1 April 2025
ISD became mandatory
Notification 16/2024 - over a year in force
Mandatory since 1 April 2025
Input Service Distributor Compliance - The Mandate Most Multi-GSTIN Businesses Missed
If your business has multiple GSTINs under one PAN and common input service invoices land at head office, ISD is no longer optional. We set up the registration, Rule 39 distribution, ISD invoices, RCM credit flow, and monthly GSTR-6 cycle.
- ISD applicability assessment for multi-GSTIN PANs
- Separate ISD registration setup
- Rule 39 pro-rata credit distribution engine
- Monthly GSTR-6 filing by the 13th
- RCM credit distribution under the 2025-26 framework
13th
GSTR-6 monthly deadline
Distribution in the same month, every month
Separate
ISD registration
Additional to your regular GSTINs
Services only
What ISD distributes
Goods and capital goods stay with the branch
For multi-GSTIN businesses
GST credit systems for growing groups
Built for companies with shared service invoices
Mandate live since
0
The ISD requirement has been in force from 1 April 2025.
Monthly filing date
0th
GSTR-6 must be filed every month after reconciling 6A and distribution.
GSTIN structures reviewed
0+
Multi-state registrations, franchise groups, and head-office invoice flows mapped.
What is Input Service Distributor compliance?
An Input Service Distributor (ISD) is a separately registered office of a business that receives invoices for common input services - such as rent, audit fees, or software licences - and distributes the input tax credit to the business's other GSTINs through ISD invoices under Rule 39, a mechanism made mandatory from 1 April 2025 by Notification No. 16/2024-Central Tax.
The mandate catches any multi-GSTIN PAN with shared service invoices, which includes many multi-state retailers, franchise groups, corporate offices, SaaS-heavy businesses, and brands with central legal, audit, software, rent or marketing invoices.
The old shortcut was cross-charge. For third-party common input services, cross-charge is no longer a substitute. If branches claim credit directly on head-office invoices, the credit can be treated as wrongly availed ITC with interest exposure.
ISD machinery
What we set up and run for you
ISD Applicability Assessment
We audit your PAN's GSTIN map and vendor invoices for common services billed to one office and consumed by many. If shared rent, audit, SaaS, legal or marketing invoices exist, we quantify exposure since April 2025.
ISD Registration Setup
We file the distinct ISD registration, configure the vendor-instruction pack, and restructure invoice flow so common-service suppliers bill the ISD GSTIN where the law expects credit to land.
Rule 39 Distribution Engine
Pro-rata by turnover, eligible and ineligible separated, tax heads tracked, exempt-supply branches included. We run the monthly computation and issue compliant ISD invoices to each recipient GSTIN.
GSTR-6 Filing
Filed by the 13th every month and reconciled against GSTR-6A auto-population. We run the cycle so one missed ISD return does not starve every branch of credit.
RCM Credit Distribution
Reverse-charge credits, including inter-state IGST-RCM, now flow through ISD under Rule 39(1A). We fold RCM invoices into the monthly distribution so credit does not strand at head office.
ISD exposure paths
Where multi-GSTIN businesses usually discover the problem
Multi-state retailer
HO claims all shared-service credit
ISD set up, back-period regularized
Franchise group
Audit fee billed to HO
Distribution engine running monthly
GSTR-6 never filed
Branch credits frozen, notices arriving
Backlog filed, cycle restored
RCM legal fees
Credit stuck at HO
Rule 39(1A) distribution added
Mandatory machinery
The machinery the mandate demands
ISD compliance is not just a registration. It is a recurring monthly credit-distribution system that touches vendors, branches, ledgers, tax heads, and return filing.
Notification 16/2024 ended the optional era from 1 April 2025.
Rule 39 requires pro-rata allocation, eligible/ineligible separation, and tax-head discipline.
GSTR-6 and GSTR-6A create a monthly cycle due by the 13th.
Finance Act 2025 and 2026 refinements bring RCM credits into the ISD machinery.
Process
How we build your ISD compliance system
- 1
GSTIN-map and invoice audit
Step 1We map all GSTINs under the PAN and identify common-service invoices, vendor patterns, branches and exposure.
- 2
ISD registration filed
Step 2A separate ISD registration is prepared and filed with authorized signatory and head-office details.
- 3
Vendor re-instruction
Step 3Common-service vendors are instructed to bill the ISD GSTIN so future credit lands in the right flow.
- 4
Monthly computation
Step 4GSTR-6A, common-service invoices, RCM self-invoices and turnover data feed the Rule 39 distribution.
- 5
ISD invoices and GSTR-6
Step 5ISD invoices are issued to recipient GSTINs and GSTR-6 is filed by the 13th.
- 6
Quarterly health check
Step 6We verify credit landed correctly at every branch and catch mismatches before notices arrive.
Documents
Documents and data needed for ISD setup
- PAN
- Existing GSTIN list
- Authorized signatory KYC
- Head-office premises proof
- Common-service vendor invoices
- Branch-wise turnover data
- Section 17(5) classification
- GSTR-6A download
- RCM self-invoices
- Prior-month ISD invoice register
Document requirements can vary by entity type and state. Our team shares a final checklist after reviewing your case.
Compliance gaps
Where ISD non-compliance hurts - and how we fix it
The risk
Still using cross-charge for third-party services
The business has been non-compliant since April 2025 for shared vendor services.
How we handle it
We migrate to ISD with a back-period strategy and clean future flow.
The risk
Branches claiming HO-invoice credit directly
Credit may be treated as wrongly availed and reversible with interest.
How we handle it
We correct vendor billing and recipient credit flow at source.
The risk
Same-month distribution missed
Credit timing breaks and GSTR-6A mismatches accumulate.
How we handle it
We run a calendared monthly engine with defined cut-offs.
The risk
Ineligible ITC distributed as eligible
Recipient-side exposure multiplies across every branch.
How we handle it
Every cycle includes Section 17(5) classification before distribution.
The risk
RCM credits ignored
Credit leaks or strands at head office.
How we handle it
Rule 39(1A) RCM coverage is built into the computation.
FAQ
ISD compliance questions, answered
Clear answers for multi-GSTIN businesses dealing with common input services, Rule 39, GSTR-6 and branch credit distribution.
Fast answersExpert support
- An Input Service Distributor is a separately registered office that receives invoices for common input services and distributes the input tax credit to the business's other GSTINs through ISD invoices.
- Yes. ISD is mandatory from 1 April 2025 for multi-GSTIN taxpayers under one PAN that receive common input service invoices used by multiple registrations.
- A taxpayer with multiple GSTINs under the same PAN should register as ISD when one office receives third-party common input service invoices such as rent, audit, legal, marketing, or software costs used by other GSTINs.
- GSTR-6 is the monthly return filed by an ISD to distribute eligible input tax credit. It is due by the 13th of the following month and is reconciled with GSTR-6A.
- Rule 39 governs ISD credit distribution, including pro-rata turnover allocation, eligible and ineligible ITC separation, tax-head tracking, credit notes, and distribution to recipient GSTINs.
- No. ISD distributes credit only on input services. Goods and capital goods credits should stay with the GSTIN that receives or uses those goods.
- ISD distributes third-party common input service credit, while cross-charge applies to internally generated supplies or services between registrations of the same legal entity.
- Credit is generally apportioned among eligible recipient GSTINs using turnover-based Rule 39 mechanics, while eligible and ineligible credits are tracked separately.
- Ineligible ITC under Section 17(5) must be identified and distributed separately as ineligible credit so recipient branches do not claim it incorrectly.
- Yes. From 1 April 2025, the ISD framework explicitly covers distribution of reverse charge credits, including inter-state IGST-RCM under Rule 39(1A).
- If GSTR-6 is not filed, branch credits can be delayed or blocked, mismatches may arise, and the business may receive compliance notices for undistributed or wrongly claimed ITC.
- The ISD framework was refined further from 1 April 2026, especially around the statutory mechanics for credit distribution and reverse charge credit handling.
Related services
Build the full multi-GSTIN GST stack
Multi-GSTIN Stack
Filing
Credit Health
The mandate is a year old. The notices are starting.
If common input service invoices still sit at head office, get your ISD registration, Rule 39 distribution, and GSTR-6 filing cycle running now.
Separate ISD registration. Monthly GSTR-6. Branch-wise credit discipline.