ISD Return Form GSTR-6 Filing Process and ITC Distribution

Managing multi-branch operations across different states under a single PAN requires strict segregation between corporate expenses. When your corporate office contracts for enterprise cloud servers, statutory brand audits, pan-India advertising campaigns, or legal advisory, those third-party invoices land at your headquarters with central GSTIN details. Because those input services benefit units in multiple states, the credit cannot remain parked at headquarters.

Following statutory amendments to Section 20 of the CGST Act, centralized distribution of common vendor services through an Input Service Distributor is mandatory. The core compliance vehicle for this distribution is Form GSTR-6. Knowing how Form GSTR-6 auto-populates from vendor filings, how turnover ratios apply under Rule 39, and how blocked credits must be handled prevents demand notices under Section 74A.

Statutory framework under Section 20 and Rule 39

The Input Service Distributor mechanism operates under Section 20 of the CGST Act, read with Rule 39 of the CGST Rules. Under Section 24(viii), any office receiving tax invoices for input services on behalf of distinct persons must obtain a dedicated ISD registration.

Section 20(2) specifies that an Input Service Distributor distributes credit against an ISD invoice issued under Rule 54(1). The key statutory conditions governing distribution include:

Credit limit: The credit distributed cannot exceed the total amount of input tax credit available for distribution in that period.
Specific recipient attribution: Credit for an input service attributable exclusively to one distinct recipient is distributed solely to that recipient.
Pro rata turnover allocation: Credit for an input service attributable to more than one recipient is distributed among those operational recipients pro rata based on their turnover during the relevant period.
Separate tracking: Eligible credit and ineligible credit under Section 17(5) must be computed, declared, and distributed as distinct line items.

Common mistake: Attempting to offset outward liabilities using the ISD GSTIN. An Input Service Distributor cannot make outward taxable supplies or discharge tax liabilities. An ISD is solely a distribution hub that receives inward tax invoices and distributes credit. It does not possess an electronic cash ledger for tax payment.

Filing deadline and structure of Form GSTR-6

Under Section 39(4) of the CGST Act and Rule 65 of the CGST Rules, every ISD must furnish Form GSTR-6 electronically on or before the 13th day of the month succeeding the calendar month.

Form GSTR-6 comprises distinct tables designed to capture inward supplies, credit distribution, and adjustments:

Table	Description	Operational function
Table 3	Input tax credit received for distribution	Auto-populated from suppliers' Form GSTR-1, Form GSTR-1A, and IFF submissions.
Table 4	Total ITC available and eligible / ineligible ITC	Summary reconciliation of total credit received, split into eligible and ineligible portions.
Table 5	Distribution of input tax credit reported in Table 4	Invoice-level distribution details mapped to recipient state GSTINs.
Table 6	Amendments to distributed credit from earlier returns	Corrects distribution ratios or amounts reported in prior months via ISD credit or debit notes.
Table 8	Input tax credit received through debit or credit notes	Auto-populated downward or upward revisions made by original vendors.
Table 9	Redistribution of credit due to debit or credit notes	Allocates vendor debit notes or credit notes to recipient units using the revised turnover ratio.

Inward records flow into the draft Form GSTR-6 via Form GSTR-6A, which generates on a dynamic basis as suppliers file their Form GSTR-1. After the 11th of the month, once monthly suppliers finish filing outward returns, the ISD team reconciles GSTR-6A records against inward purchase registers before finalizing Table 5 distributions on the 13th.

ISD invoice requirements under Rule 54(1)

To pass credit legally to distinct branches, an ISD issues an ISD invoice under Rule 54(1) of the CGST Rules. Unlike regular commercial invoices issued under Section 31, an ISD invoice does not state taxable supply values or HSN codes. Instead, it acts as a credit transfer instrument.

An ISD invoice must contain the following details:

Name, address, and 15-digit GSTIN of the Input Service Distributor.
A consecutive serial number not exceeding 16 characters, containing alphabets, numerals, or special characters (hyphen or slash), unique for a financial year.
Date of issue of the ISD invoice.
Name, address, and GSTIN of the recipient distinct branch.
Amount of input tax credit distributed, clearly showing separate figures for central tax, state tax, and integrated tax.
A clear statement indicating whether the credit represents eligible ITC or ineligible credit under Section 17(5).
Signature or digital signature of the ISD or its authorized representative.

Turnover ratio distribution formula under Section 20(2)

When an input service relates to multiple branches, credit distribution follows the statutory turnover formula under Section 20(2) and Rule 39(1)(d). The share distributed to recipient branch 'A' is computed as:

Distributed Credit = (Turnover of Recipient Unit A ÷ Total Turnover of all Operational Recipient Units) × Total Common ITC

Defining the relevant turnover period

Under Explanation (c) to Section 20, the turnover period used for the allocation formula is determined as follows:

If all recipient operational units have turnover in their state during the preceding financial year, that preceding financial year's turnover figures are used.
If any operational recipient unit did not have turnover in the preceding financial year, the turnover of the last quarter for which turnover figures are available for all recipients prior to the month of distribution is used.

Turnover in this context refers to aggregate turnover in each recipient state under Section 2(6) of the CGST Act, excluding central tax, state tax, and integrated tax.

Eligible vs ineligible credit distribution

One of the most scrutinised areas during GST audits is the treatment of blocked credits. When a corporate office procures services that fall under Section 17(5), such as general employee catering, non-obligatory corporate health insurance, or works contract services for building alterations capitalized to office buildings, the ISD cannot filter out the credit and absorb it.

Under Rule 39(1)(e), an Input Service Distributor must distribute both eligible and ineligible credits separately:

Ineligible credit segregation: Ineligible credit must be identified at the time of processing the supplier invoice.
Separate ISD invoices: The ISD issues separate ISD invoices or distinct line items identifying the exact tax amount that is ineligible under Section 17(5).
Reporting in Form GSTR-6: In Table 4, the ISD enters the split between eligible ITC and ineligible ITC. This flows into Table 5 distribution schedules.
Recipient branch compliance: When the recipient branch receives the auto-populated credit in its Form GSTR-2B, the ineligible amount appears in Part B. The recipient unit includes the full amount in Table 4(A)(4) of Form GSTR-3B and simultaneously reverses the ineligible portion in Table 4(B)(1) as an absolute permanent reversal.

Notice risk: If an ISD marks blocked vendor services as eligible credit and distributes them without demarcation, recipient units claim the ITC in Table 4(A)(4) without reversal. During tax audits, tax authorities issue notices under Section 74A, demanding tax recovery along with 18% interest under Section 50 and penalties.

CGST, SGST, and IGST cross-state conversion rules

When an ISD distributes credit, the tax head changes depending on the geographical location of the supplier, the ISD, and the recipient branch. Under Rule 39(1)(e) and (f), conversion follows these statutory rules:

Tax type on vendor invoice	ISD location vs recipient branch	Distributed tax head on ISD invoice
Integrated Tax (IGST)	Same state or different state	Distributed as Integrated Tax (IGST)
Central Tax (CGST) and State Tax (SGST)	Located in the SAME state as ISD	Distributed as CGST and SGST respectively
Central Tax (CGST) and State Tax (SGST)	Located in a DIFFERENT state from ISD	Converted and distributed as Integrated Tax (IGST)

When intra-state credit (CGST and SGST) is distributed to an out-of-state recipient, the ISD combines the amounts and issues the ISD invoice as integrated tax (IGST). For example, if headquarters in Maharashtra receives an invoice with ₹9,000 CGST and ₹9,000 SGST, and allocates 50% to its Karnataka branch, the distributed amount for Karnataka becomes ₹9,000 IGST.

Worked numerical example: corporate headquarters distribution

Consider Apex Industries Limited, with corporate headquarters located in Mumbai, Maharashtra (ISD GSTIN: 27AAAAA1111A1Z1). The company operates manufacturing and distribution facilities across three distinct state GSTINs:

Maharashtra manufacturing unit: 27AAAAA1111A2Z2
Gujarat processing plant: 24AAAAA1111A1Z8
Karnataka distribution warehouse: 29AAAAA1111A1Z4

During the tax period of September 2026, all three units were operational. State turnovers during the preceding financial year (FY 2025-26) were as follows:

Maharashtra unit turnover: ₹50,00,00,000 (50% share)
Gujarat plant turnover: ₹30,00,00,000 (30% share)
Karnataka warehouse turnover: ₹20,00,00,000 (20% share)
Total organization turnover: ₹100,00,00,000 (100%)

In September 2026, the corporate ISD receives two vendor invoices for common corporate input services:

Invoice A (Enterprise Cloud Hosting): Inter-state supply from Bengaluru with IGST of ₹10,00,000. Fully eligible business input service.
Invoice B (Executive Health Insurance): Intra-state supply from Mumbai with ₹2,00,000 CGST and ₹2,00,000 SGST (Total ₹4,00,000). Ineligible credit under Section 17(5)(b)(i), as health insurance was not mandatory under any law for these employees.

Distribution calculations

Total eligible IGST to distribute is ₹10,00,000. Total ineligible credit to distribute is ₹4,00,000 (consisting of ₹2,00,000 CGST and ₹2,00,000 SGST).

Recipient unit	Turnover ratio	Eligible ITC (IGST)	Ineligible ITC (Section 17(5))	Tax head for ineligible ITC	Total distributed
Maharashtra (Same state)	50%	₹5,00,000	₹2,00,000	CGST ₹1,00,000 + SGST ₹1,00,000	₹7,00,000
Gujarat (Inter-state)	30%	₹3,00,000	₹1,20,000	Converted to IGST ₹1,20,000	₹4,20,000
Karnataka (Inter-state)	20%	₹2,00,000	₹80,000	Converted to IGST ₹80,000	₹2,80,000
Total	100%	₹10,00,000	₹4,00,000	Merged heads	₹14,00,000

The ISD files Form GSTR-6 on 12 October 2026. On 14 October 2026, when Form GSTR-2B is generated for each recipient GSTIN, the entries reflect in Part B. Each branch accounts for its received credit in Form GSTR-3B for September 2026 as follows:

Gujarat branch: Declares ₹4,20,000 under Table 4(A)(4) (Inward supplies from ISD) and enters ₹1,20,000 under Table 4(B)(1) as ineligible credit reversal. Net available credit utilized against output liability is exactly ₹3,00,000.
Karnataka branch: Declares ₹2,80,000 under Table 4(A)(4) and enters ₹80,000 under Table 4(B)(1) as permanent reversal. Net available credit utilized is ₹2,00,000.
Maharashtra branch: Declares ₹7,00,000 under Table 4(A)(4) (split by IGST ₹5,00,000, CGST ₹1,00,000, SGST ₹1,00,000) and enters ₹2,00,000 under Table 4(B)(1). Net available credit is ₹5,00,000.

Step-by-step procedure to prepare and file Form GSTR-6 online

To prepare and file Form GSTR-6 on the GST common portal, follow these verified portal steps:

Log in to the GST Portal using your ISD login credentials.
Navigate to Services > Returns > Returns Dashboard.
Select the relevant Financial Year and Return Filing Period, then click Search.
On the Form GSTR-6 tile, click Prepare Online.
Review Table 3 (ITC Received) and Table 6B (ITC Received via Debit or Credit Notes). Compare the auto-populated figures with your internal accounting register. If any vendor invoice is missing or incorrect, edit or add records directly.
Click on Table 4 to confirm total eligible and ineligible ITC available for distribution.
Open Table 5 and input the distribution details across each recipient branch GSTIN based on the computed turnover ratio. Ensure that the total distributed amount matches the available credit exactly.
Click Calculate ITC and review the summary page.
Click Proceed to File, select the declaration checkbox, choose the authorized signatory from the drop-down list, and submit the return using either DSC or EVC.

Common pitfalls in Form GSTR-6 filing and distribution

Audit inspections frequently uncover routine compliance failures in ISD operations. Watch out for these operational traps:

Distributing credit to non-operational units: Including a branch GSTIN that was closed or non-operational during the relevant period distorts the turnover ratio and leads to unabsorbed credit.
Omitting vendor credit notes: When an original vendor issues a credit note reducing service charges, the ISD must reflect the credit note in Table 8 and redistribute the reduction in Table 9. Failing to distribute negative credit leads to excess credit claims at recipient branches.
Confusing ISD with cross charge: An ISD cannot distribute costs relating to internal head office employee salaries or management oversight. Internal head office services must be handled through cross charge invoices under Section 31. For detailed differences, refer to our analysis on cross charge vs ISD rules and the mandatory ISD registration guidelines.
Failing to file GSTR-6 before recipient 3B deadlines: If Form GSTR-6 is filed after the 13th, the credit will not reflect in the recipient units' Form GSTR-2B generated on the 14th. Recipient units cannot legally claim provisional credit in GSTR-3B under Rule 36(4).

Related guides

Frequently asked questions

What is the filing deadline for Form GSTR-6?

Under Section 39(4) of the CGST Act and Rule 65 of the CGST Rules, an Input Service Distributor must file Form GSTR-6 electronically on or before the 13th day of the month succeeding the calendar month.

Can an Input Service Distributor retain undistributed input tax credit in Form GSTR-6?

No. Under Section 20 and Rule 39, an Input Service Distributor acts strictly as a credit pass-through facility. All input tax credit received in a given tax period must be distributed in that same tax period via Form GSTR-6.

How does an ISD distribute credit blocked under Section 17(5)?

Under Rule 39(1)(e), an Input Service Distributor must segregate eligible credit and ineligible credit, distributing both separately. The ISD issues an ISD invoice clearly marking the credit as ineligible so recipient branches report it as ineligible credit in Table 4(B)(1) or Table 4(D) of Form GSTR-3B.

How do recipient branches receive credit distributed through Form GSTR-6?

Once the ISD files Form GSTR-6 on the portal, details auto-populate into Part B of Form GSTR-2B for each recipient branch under Table 4(A)(4) of Form GSTR-3B as inward supplies from ISD.

Reconcile branch purchase registers against Form GSTR-2B

When recipient branches receive ISD credit alongside regular vendor invoices, matching purchase ledgers against Form GSTR-2B ensures no credit is missed or double counted. Your GSTR-2B and purchase register files are read in your browser and never uploaded to any server.

Reconcile GSTR-2B →

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Last checked: 18 October 2026. Sources: Section 20 CGST Act, Rule 39 CGST Rules, Notification 16/2024-Central Tax.