ISD Under GST —
Meaning, GSTR-6 Filing,
Due Dates & Penalties
Everything a business, CA, or tax professional needs to know about Input Service Distributors — from the statutory definition to step-by-step GSTR-6 filing and the complete penalty framework.
Vide Notification No. 16/2024-Central Tax dated 06 August 2024, the ISD mechanism has been made mandatory for all eligible businesses effective 01 April 2025. Prior to this, ISD registration was optional. Any business distributing common input service ITC across branches must now mandatorily register as an ISD and file GSTR-6 every month.
What Is an Input Service Distributor?
An Input Service Distributor (ISD) is a specific type of GST registrant — typically the Head Office or central procurement unit of a business — that receives tax invoices for input services used by multiple branches or units, and distributes the corresponding Input Tax Credit (ITC) to those branches in accordance with the prescribed rules under GST law.
In simpler terms: when a company's Head Office (HO) pays for services — like IT support, software subscriptions, audit fees, legal services, or telecom — that are actually used across multiple branch offices in different states, the HO cannot retain all the ITC. Instead, it registers as an ISD and distributes the ITC to each branch through ISD invoices, which the branches then use to claim credit in their respective GSTR-3B returns.
ISD is specifically designed for entities where multiple GST registrations exist under the same PAN. For example, a company with a Head Office in Mumbai and branches in Chennai, Hyderabad, and Delhi — all with separate GSTINs but the same PAN — is a classic ISD scenario.
ABC Ltd. has its Head Office in Mumbai with branches in Chennai and Delhi. It pays ₹10 lakh + GST ₹1.8 lakh for an annual IT services subscription used by all three offices.
The HO receives the invoice, claims ITC of ₹1.8 lakh as ISD, and distributes proportionate credit to Chennai and Delhi branches via ISD invoices. Each branch reports the received ITC in their GSTR-3B. The HO reports the entire distribution in GSTR-6.
Key Features & Characteristics of ISD
An ISD is typically the Head Office, registered office, or a dedicated central procurement unit of the business — not the branch offices themselves.
ISD must obtain a separate GST registration as "Input Service Distributor" — different from its regular taxpayer GSTIN, even in the same state.
ISD mechanism applies exclusively to input services. ITC on goods or capital goods cannot be distributed through the ISD mechanism under GST.
The distributing ISD and all recipient branches must have the same Permanent Account Number (PAN). Cross-PAN ITC distribution is not permitted under this mechanism.
Unlike regular taxpayers, an ISD registrant does not maintain an Electronic Credit Ledger. It can only distribute the ITC received — not utilize it for its own tax payment.
Reverse Charge Mechanism (RCM) does not apply to an ISD. If RCM applies to a supply, the ISD must separately register as a regular taxpayer for that purpose.
ISD vs Regular GST Taxpayer
- Separate GST registration as ISD
- Receives invoices for services used by branches
- Distributes ITC to branches via ISD invoices
- Files GSTR-6 monthly (by 13th)
- No Electronic Credit Ledger
- Cannot pay its own output tax liability from ISD registration
- No RCM liability under ISD registration
- ITC can be eligible or ineligible — both types distributable
- Standard GSTIN registration
- Receives invoices for own business use
- Claims ITC in its own Electronic Credit Ledger
- Files GSTR-1, GSTR-3B monthly
- Maintains full Electronic Credit Ledger
- Pays output tax using ITC or cash
- RCM applicable on notified supplies
- ITC only for eligible supplies under Section 16
ITC Distribution Rules — How Credit Is Apportioned
The ISD distributes ITC to recipient branches using ISD invoices or ISD credit notes. The apportionment rules under Section 20 of the CGST Act (as amended effective 01 April 2025) and Rule 39 of the CGST Rules govern how credit must be allocated.
Distribution Formula — Proportionate Turnover Method
Types of ISD Documents
| Document Type | When Issued | Effect on Recipient |
|---|---|---|
| ISD Invoice | When distributing ITC of original invoice | Recipient gets ITC credited in their GSTR-2B |
| ISD Credit Note | When original ITC is reduced (supplier issues credit note) | Recipient ITC reduced; may add to output liability if negative |
| ISD Debit Note | When additional ITC becomes distributable | Recipient gets additional ITC |
Sections 20(1) and 20(2) of the CGST Act were amended, effective 01 April 2025, to explicitly permit distribution of ITC on inter-State supplies under Reverse Charge (Section 5(3) and 5(4) of IGST Act) through the ISD mechanism. This closes a significant earlier gap where cross-border RCM IGST credits could not be routed through ISD.
What Is GSTR-6?
GSTR-6 is the monthly GST return that every registered Input Service Distributor is mandatorily required to file. It is the official mechanism through which an ISD reports to the Government:
- 1Which invoices (inward supplies of services) were received by the ISD during the month, and the ITC available thereon.
- 2Total eligible and ineligible ITC available for distribution, segregated by IGST, CGST, and SGST/UTGST.
- 3How the ITC was distributed to each recipient branch — the GSTIN-wise, invoice-wise allocation of ISD invoices and ISD credit notes.
- 4Any amendments, corrections, or redistribution of ITC distributed in earlier return periods.
- 5Details of any refund claimed from the Electronic Cash Ledger by the ISD.
The GST portal auto-populates GSTR-6A for the ISD — a read-only form that contains invoice-wise details of inward supplies as reported by the ISD's suppliers in their GSTR-1. The ISD must verify GSTR-6A data and then file GSTR-6 by accepting, modifying, or adding missing details. Matching with GSTR-2B is critical before filing.
Who Must File GSTR-6?
| Criteria | GSTR-6 Applicable? | Reason |
|---|---|---|
| Registered as ISD under GST | Mandatory | Primary condition for filing GSTR-6 |
| No ITC received or distributed in the month | Mandatory (NIL) | NIL return is still compulsory |
| Regular taxpayer (not ISD) | Not Applicable | Files GSTR-1 and GSTR-3B instead |
| Composition taxpayer | Not Applicable | Files GSTR-4 only |
| Business with multi-state branches (post Apr 2025) | Mandatory to register & file | ISD mechanism now mandatory for eligible entities |
Even if an ISD has no ITC to distribute in a particular month, it must still file a NIL GSTR-6. Non-filing of a NIL return will attract late fees just like any other missed return. There are no exceptions to the monthly filing obligation.
GSTR-6 Format — All 11 Tables Explained
GSTR-6 consists of 11 tables (sections) that together capture the complete picture of ITC received and distributed by the ISD during the month. Understanding each table is essential for error-free filing.
1–2Auto
Basic identification details of the ISD — GSTIN and legal name as per GST registration, and the tax period (month-year) for which the return is being filed.
Auto-Populated3Key
Invoice-wise details of all inward supplies received by the ISD during the month where ITC is available for distribution. Auto-populated from GSTR-6A (supplier's GSTR-1). The ISD must verify, accept, or correct before submitting. Contains GSTIN of supplier, invoice number, date, taxable value, and IGST/CGST/SGST amounts.
Auto-Populated from GSTR-6A Manual Additions Allowed4
A summary view of the total ITC available to the ISD for the period, split between eligible ITC (for distribution to branches) and ineligible ITC (blocked under Section 17(5) or otherwise not distributable). Auto-populated from Table 3 data.
System Computed5Critical
The most critical table. The ISD reports the actual distribution of ITC to each recipient branch via ISD invoices. For each ISD invoice, the table captures: recipient GSTIN, ISD invoice number & date, and IGST/CGST/SGST amounts distributed. Both eligible and ineligible ITC distribution is reported here. Once filed, this data flows to the recipient branch's GSTR-2B.
Critical — Manual Entry Required6A/6B/6C
Used to correct or amend details reported in earlier GSTR-6 returns. 6A: Amendment to inward supply invoices. 6B: Amendment to debit notes received. 6C: Amendment to credit notes received. GSTR-6 cannot be revised after filing — all corrections must be made through these amendment tables in subsequent months.
Manual — Amendment Only7
Reports ITC mismatches identified between the ISD's GSTR-6 and supplier's GSTR-1. Any mismatch liability is added to the ISD, which must then issue an ISD credit note to reduce distributed credit. Also used for reclaiming ITC previously reversed due to mismatch.
Manual Review Required8
Where credit is to be reduced (because the original supplier issued a credit note), the ISD issues ISD credit notes and reports them here. The apportionment of credit reduction follows the same ratio as the original ISD invoice distribution.
Manual Entry9
Used when previously distributed ITC needs to be redistributed — for example, when a branch is deregistered, or the original apportionment ratio needs correction based on revised turnover data. Redistributed ITC is allocated among the remaining or corrected set of recipient branches.
Conditional Use10
Auto-computed by the GST portal. Displays the late fee payable if the return is being filed after the due date (13th of the subsequent month). Late fee must be paid before the return can be submitted. This table is accessible only after the return is filed.
System Computed11
If the ISD has any balance in the Electronic Cash Ledger (from earlier payments) and wishes to claim a refund, the details are entered here. Filing a refund claim through Table 11 results in a debit entry in the Electronic Cash Ledger of the ISD.
OptionalStep-by-Step GSTR-6 Filing Guide
GSTR-6 for a tax period (month M) can only be filed on or after the 10th day of month M+1 and must be filed on or before the 13th day of month M+1. Example: For April 2026, filing window is 10 May 2026 to 13 May 2026.
Login to GST Portal
Visit gst.gov.in and log in using the ISD GSTIN credentials (not the regular taxpayer GSTIN). Navigate to: Services → Returns → Returns Dashboard.
Select Tax Period & Access GSTR-6
From the Returns Dashboard, select the financial year and the tax period (month). Click on GSTR-6 to open the return. Select "Prepare Online" for manual entry or "Prepare Offline" if using the GST offline tool.
Verify GSTR-6A Auto-Populated Data (Table 3)
Review all auto-populated inward supply details in Table 3 (sourced from suppliers' GSTR-1 via GSTR-6A). Verify each invoice — accept correct entries, modify incorrect ones, and manually add any missing invoices not reflected in GSTR-6A.
Review Total ITC Summary (Table 4)
Verify the auto-computed total ITC available, split between eligible and ineligible. Confirm the segregation aligns with your books — particularly the Section 17(5) blocked credit classification.
Enter ISD Invoice Distribution Details (Table 5)
This is the most critical step. For each ISD invoice issued during the month, enter: recipient branch GSTIN, ISD invoice number and date, and the IGST/CGST/SGST amounts distributed. Apply the turnover-based proportionate apportionment or specific attribution as applicable under Rule 39.
Enter ISD Credit Notes (Table 8) — If Applicable
If any supplier has issued a credit note reducing ITC during the period, report the corresponding ISD credit notes issued to branches in Table 8. Apportion the reduction in the same ratio as the original ISD invoice distribution.
Enter Amendments or Redistributions (Tables 6A/6B/6C & 9) — If Required
If any earlier period data needs correction, use Tables 6A/6B/6C for invoice amendments. Use Table 9 for redistribution of ITC from earlier periods (e.g., due to branch deregistration or ratio correction).
Preview Return & Verify Totals
Use the Preview function to generate a PDF of the return. Cross-verify: (a) total ITC received matches books, (b) total ITC distributed equals total ITC received, (c) each branch's allocation is correct. Total IGST+CGST+SGST available must always equal total distributed (including any negative distribution adjustments).
Pay Late Fee (If Applicable)
If filing after the 13th, the portal auto-computes the late fee in Table 10. Pay the late fee through the Electronic Cash Ledger before proceeding. GSTR-6 cannot be filed without clearing the outstanding late fee.
Submit & File Using DSC or EVC
Click Submit to freeze the return data. Then proceed to File using either DSC (Digital Signature Certificate) for companies and LLPs, or EVC (Electronic Verification Code) for other taxpayers. Once filed, an Acknowledgment Reference Number (ARN) is generated.
GSTR-6 can also be filed using the GST Offline Utility Tool available for download from the portal. The following sections can be populated offline: Invoice Details (Table 3), Credit/Debit Note Details, Distribution of ITC (Tables 5 & 8), Redistribution of ITC (Table 9), and Amendments (Tables 6A, 6B, 6C). The JSON file generated offline is then uploaded to the portal for final submission.
GSTR-6 Due Dates — Monthly Calendar
The statutory due date for filing GSTR-6 is the 13th day of the month immediately following the tax period. This is fixed under the CGST Act and applies uniformly to all ISD registrants regardless of turnover or state.
| Tax Period | Due Date | Filing Window Opens | Remarks |
|---|---|---|---|
| Each Calendar Month | 13th of following month | 10th of following month | Fixed statutory date |
| No annual return | N/A | N/A | Only monthly filing; no GSTR-9 equivalent for ISD |
| Extension by Government | Notified date | As notified | CBIC may extend via notification in specific situations |
Unlike regular taxpayers who file GSTR-9 annually, there is no annual return prescribed for ISD registrants. GSTR-6 filings are exclusively monthly. This makes timely monthly compliance especially important — there is no annual reconciliation opportunity to catch errors.
Penalties for Late Filing & Non-Compliance
/day
Where there is ITC to be distributed and the return is filed late, a late fee of ₹25 per day under CGST + ₹25 per day under SGST = ₹50 per day total is levied under Section 47 of the CGST Act. This accrues from the day after the due date (14th) until the actual date of filing.
/day
Unlike GSTR-3B where NIL returns attract a reduced late fee of ₹20/day, no specific reduction has been notified for NIL GSTR-6 returns by the CBIC. Therefore, the standard ₹50/day late fee applies even for NIL GSTR-6 filings. The system automatically blocks filing until the fee is paid.
p.a.
If ITC is incorrectly distributed by the ISD and wrongly availed by recipient branches, interest at 18% per annum under Section 50 of the CGST Act is levied on the recipient for the period of wrong availment. If the error involves fraud, the interest rate rises to 24% per annum under Section 50(3).
100%
Recovery proceedings under Section 73 (non-fraud) or Section 74 (fraud/suppression) may be initiated. For FY 2024-25 onwards, proceedings are governed by the newly inserted Section 74A (Finance (No.2) Act, 2024). Penalty under Section 122 can extend up to 100% of the ITC wrongly distributed or availed in fraud cases.
Lost
When GSTR-6 is not filed on time, the distributed ITC does not reflect in the recipient branches' GSTR-2B for that period. Branches cannot claim the ITC they are entitled to, leading to cash flow stress at the branch level, incorrect GSTR-3B filing, or delays in ITC availment.
Penalty Summary Table
| Default | Penalty / Consequence | Legal Provision |
|---|---|---|
| Late filing of GSTR-6 | ₹50 per day (₹25 CGST + ₹25 SGST) | Section 47, CGST Act |
| Wrong ITC distribution | Interest @ 18% p.a. on wrongly availed ITC | Section 50(1), CGST Act |
| Fraud / suppression | Interest @ 24% p.a. + penalty up to 100% | Sections 50(3) & 74/74A |
| Delayed payment by recipient post-notice | 10% of tax or ₹10,000 (whichever higher) | Section 73, CGST Act |
| Non-filing continuously | Compliance notice + possible registration suspension | Section 29(2), CGST Act |
| ITC mismatch not resolved | Added to ISD liability; ISD must issue credit notes | Rule 39, CGST Rules |
Common Errors & How to Avoid Them
| # | Common Error | Consequence | How to Avoid |
|---|---|---|---|
| 1 | Incorrect recipient GSTIN in Table 5 | ITC not reflected in correct branch's GSTR-2B | Maintain verified branch GSTIN master list; validate on GSTN portal before entry |
| 2 | Wrong apportionment ratio applied | Branches receive incorrect ITC; redistribution needed later | Calculate turnover-based ratio from latest audited financials; update quarterly |
| 3 | Using regular GSTIN instead of ISD GSTIN to log in | Return filed in wrong entity; creates compliance mess | Clearly label ISD credentials; use separate browser profile for ISD login |
| 4 | Missing invoices not in GSTR-6A | ITC for those invoices not distributed | Reconcile GSTR-6A with purchase register before Table 3 verification |
| 5 | Forgetting NIL return for months with no ITC | Late fee accumulates; portal blocks future filings | Set calendar reminder for 13th of every month regardless of ITC activity |
| 6 | Not issuing ISD credit notes when supplier issues credit note | Branches retain excess ITC; mismatch liability | Monitor supplier credit notes monthly; issue ISD credit notes in same period |
Conclusion — ISD Compliance Is Now Non-Negotiable
With the mandatory activation of the ISD mechanism from 01 April 2025, every multi-branch business that receives common input service invoices at its Head Office must now register as an ISD, issue ISD invoices for every distribution, and file GSTR-6 every month without exception.
The ISD mechanism — when implemented correctly — ensures seamless, audit-proof distribution of ITC across the enterprise. But when ignored or implemented sloppily, it creates compounding problems: branches lose ITC, demand notices arrive, interest accrues, and audit risk escalates. The key compliance actions every ISD must take:
