Section 2(61) of the CGST Act 2017 defines ISD as: “an office of the supplier of goods or services which receives tax invoices towards receipt of input services and issues a prescribed document for the purposes of distributing the credit of central tax, State tax, integrated tax or Union territory tax paid on said services to a supplier of taxable goods or services or both having same PAN.”

In plain terms:

• ISD is a registered office — typically the head office or corporate office
• It receives service invoices and pays GST on them
• It accumulates ITC in its own GSTIN
• It then issues prescribed ISD invoices to distribute that ITC to branches
• Condition: All units must share the same PAN

The ISD mechanism is relevant for businesses where:

• There are multiple branches or units in different states — each with a separate GSTIN
• The head office procures services centrally on behalf of all units
• Common services — IT subscriptions, legal fees, audit fees, advertising — benefit all locations
• ITC is accumulating at the head office GSTIN while branches cannot access it

ISD vs Cross-Charge — Key Difference

A separate GST registration for ISD is mandatory — the existing GSTIN of the head office cannot function as an ISD. This is a point many businesses miss when setting up the ISD structure.

• The distributing office (head office) must obtain a separate ISD registration
• Same PAN — but a different GSTIN specifically for ISD
• On the GST portal registration form, select “Input Service Distributor” as the nature of business
• The ISD GSTIN is used only for distribution — it does not make taxable outward supplies

An ISD cannot distribute ITC arbitrarily. Rule 39 of the CGST Rules prescribes a mandatory turnover-based formula:

Formula:
ITC to be distributed to a unit = Total ITC × (Turnover of that unit ÷ Total turnover of all units)

Worked Example — Delhi HO with Three Branches

Turnover Calculation — Key Points

• Previous financial year’s turnover is used as the basis for distribution
• For newly established units — actual available turnover is used
• Units making exempt supplies may need to reverse a proportionate share of ITC received
• Turnover figures are sourced from GSTR-3B or the Annual Return

This is an important distinction — when distributing ITC to a unit in a different state, CGST and SGST are automatically converted to IGST. The receiving unit then uses that IGST credit in its own state for GST liability settlement.

ISD distribution requires the issuance of an ISD Invoice, prescribed under Rule 54(1) of the CGST Rules. Each ISD Invoice must contain:

• Name, address, and GSTIN of the ISD (ISD registration number)
• Consecutive serial number
• Date of issue
• Name, address, and GSTIN of the recipient unit
• Amount of ITC being distributed
• IGST / CGST / SGST / UTGST amounts — stated separately
• Reference to the original supplier’s invoice number
• Signature or digital signature of the authorised person

An ISD Credit Note can also be issued — where ITC previously distributed needs to be reversed or corrected.

ISD registration comes with a dedicated GST return — GSTR-6 — filed monthly.

GST Compliance Guide — Returns and ITC Complete Guide

Example 1: Software Company — Delhi HO + 3 Branches

TechCorp India — ISD registered at its Delhi head office. Branches in Mumbai, Pune, and Hyderabad. Annual Salesforce CRM subscription: ₹24 lakh + GST ₹4.32 lakh (18%). Invoice received at Delhi HO.

Quarterly ISD distribution (₹1.08 lakh per quarter):

• Delhi HO (35% turnover share): ₹37,800 — distributed as CGST + SGST (Delhi)
• Mumbai (25%): ₹27,000 — distributed as IGST (cross-state)
• Pune (20%): ₹21,600 — distributed as IGST (cross-state)
• Hyderabad (20%): ₹21,600 — distributed as IGST (cross-state)

ISD files GSTR-6 — all branches receive ITC in their GSTR-2B — branches claim in GSTR-3B. Full ₹4.32 lakh ITC is efficiently utilized across all locations instead of sitting idle in Delhi.

Example 2: Manufacturing Company — ISD Mandatory Post April 2025

XYZ Manufacturers — HO in Mumbai, factories in Gujarat and Rajasthan. Annual legal retainer fees: ₹12 lakh (GST ₹2.16 lakh) — paid by HO.

Before April 2025 (Cross-Charge): HO raised invoices to each factory, charging GST. Factories paid GST and then claimed it as ITC. Two-step process with working capital impact.

After April 2025 (ISD Mandatory): HO distributes ITC directly via ISD invoices — no GST charged on the distribution. Factories receive ITC directly in their GSTR-2B. Zero additional GST outflow — working capital freed up — compliance simplified.

ISD is now mandatory for common input services. However, cross-charge continues to apply in specific scenarios:

Mistake 1: Distributing ITC from the regular GSTIN without obtaining a separate ISD registration
Fix: A separate ISD registration is mandatory. Distribution made without a valid ISD registration is legally invalid — the receiving units’ ITC claims can be disallowed during assessment.

Mistake 2: Distributing ITC arbitrarily without applying the turnover-based formula
Fix: Rule 39 mandates the turnover-based formula. Discretionary allocation — giving more to one unit because it has a higher tax liability — is non-compliant and can be challenged.

Mistake 3: Filing GSTR-6 late or not filing at all
Fix: GSTR-6 must be filed by the 13th of every month. Late filing delays the update of receiving branches’ GSTR-2B — they cannot claim ITC until it appears there. Late fees also apply.
GST Late Filing Penalty — Complete Guide

Mistake 4: Continuing with cross-charge for common services after April 2025
Fix: Finance Act 2024 has made ISD mandatory for common input services. Using cross-charge for such services post April 2025 is non-compliant — ITC risk and potential penalty.

Mistake 5: Not separately mentioning IGST, CGST, SGST on ISD invoices
Fix: Each tax head must be stated separately on the ISD invoice. A consolidated amount prevents the receiving unit from correctly claiming credit against the right tax head.
GST ITC Reconciliation — GSTR-2B vs GSTR-3B Guide