What is an Input Service Distributor?

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.

Is ISD mandatory now?

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.

Who must register as ISD?

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.

What is GSTR-6 and its due date?

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.

Can ISD distribute ITC on goods?

No. ISD distributes credit only on input services. Goods and capital goods credits should stay with the GSTIN that receives or uses those goods.

What is the difference between ISD and cross-charge?

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.

How is credit apportioned between branches?

Credit is generally apportioned among eligible recipient GSTINs using turnover-based Rule 39 mechanics, while eligible and ineligible credits are tracked separately.

What about ineligible ITC?

Ineligible ITC under Section 17(5) must be identified and distributed separately as ineligible credit so recipient branches do not claim it incorrectly.

Can RCM credit be distributed?

Yes. From 1 April 2025, the ISD framework explicitly covers distribution of reverse charge credits, including inter-state IGST-RCM under Rule 39(1A).

What if GSTR-6 isn't filed?

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.

What changed on 1 April 2026?

The ISD framework was refined further from 1 April 2026, especially around the statutory mechanics for credit distribution and reverse charge credit handling.

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

1 April 2025

ISD became mandatory

Notification 16/2024 - over a year in force

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

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

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.

Input Service Distributor (ISD) compliance service with ComplyLocal

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 1
We map all GSTINs under the PAN and identify common-service invoices, vendor patterns, branches and exposure.
2
ISD registration filed
Step 2
A separate ISD registration is prepared and filed with authorized signatory and head-office details.
3
Vendor re-instruction
Step 3
Common-service vendors are instructed to bill the ISD GSTIN so future credit lands in the right flow.
4
Monthly computation
Step 4
GSTR-6A, common-service invoices, RCM self-invoices and turnover data feed the Rule 39 distribution.
5
ISD invoices and GSTR-6
Step 5
ISD invoices are issued to recipient GSTINs and GSTR-6 is filed by the 13th.
6
Quarterly health check
Step 6
We 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.

Set up ISD compliance Check applicability

Separate ISD registration. Monthly GSTR-6. Branch-wise credit discipline.

Input Service Distributor Compliance - The Mandate Most Multi-GSTIN Businesses Missed

Check ISD exposure

ISD became mandatory

GSTR-6 monthly deadline

ISD registration

What ISD distributes

GST credit systems for growing groups

Built for companies with shared service invoices

What is Input Service Distributor compliance?

What we set up and run for you

ISD Applicability Assessment

ISD Registration Setup

Rule 39 Distribution Engine

GSTR-6 Filing

RCM Credit Distribution

Where multi-GSTIN businesses usually discover the problem

The machinery the mandate demands

How we build your ISD compliance system

GSTIN-map and invoice audit

ISD registration filed

Vendor re-instruction

Monthly computation

ISD invoices and GSTR-6

Quarterly health check

Documents and data needed for ISD setup

Where ISD non-compliance hurts - and how we fix it

Still using cross-charge for third-party services

Branches claiming HO-invoice credit directly

Same-month distribution missed

Ineligible ITC distributed as eligible

RCM credits ignored

ISD compliance questions, answered

01What is an Input Service Distributor?

02Is ISD mandatory now?

03Who must register as ISD?

04What is GSTR-6 and its due date?

05What is Rule 39?

06Can ISD distribute ITC on goods?

07What is the difference between ISD and cross-charge?

08How is credit apportioned between branches?

09What about ineligible ITC?

10Can RCM credit be distributed?

11What if GSTR-6 isn't filed?

12What changed on 1 April 2026?

Build the full multi-GSTIN GST stack

Multi-GSTIN Stack

Filing

Credit Health

The mandate is a year old. The notices are starting.

Documents and data needed for ISD setup

ISD compliance questions, answered

01What is an Input Service Distributor?

02Is ISD mandatory now?

03Who must register as ISD?

04What is GSTR-6 and its due date?

05What is Rule 39?

06Can ISD distribute ITC on goods?

07What is the difference between ISD and cross-charge?

08How is credit apportioned between branches?

09What about ineligible ITC?

10Can RCM credit be distributed?

11What if GSTR-6 isn't filed?

12What changed on 1 April 2026?