How an ISD Converts Tax Heads: IGST, CGST, SGST and UTGST

ISD Converts Tax Heads explained: this guide covers what it means, who it applies to, the step-by-step process, documents required, fees, due dates and penalties in India — so you can stay compliant with confidence and avoid costly mistakes.

An ISD does something no other registration does: it changes the head of the tax as the credit passes through. The rules are short, mechanical, and produce one reconciliation quirk that surprises people the first time they see a GSTR-6 summary.

IGST credit is always distributed as IGST, to a recipient in the same State or a different one. CGST and SGST/UTGST credit is distributed as CGST and SGST/UTGST respectively where the recipient is in the same State or UT as the ISD, and as IGST where the recipient is elsewhere — the IGST amount being equal to the aggregate of the CGST and SGST/UTGST that qualified for distribution to that recipient. A recipient in an SEZ always receives IGST only, whatever its State code. Total credit in must equal total credit out each month, even though the individual heads will not tally.

The statutory basis

Section 20(3) — "The credit of central tax shall be distributed as central tax or integrated tax and integrated tax as integrated tax or central tax, by way of issue of a document containing the amount of input tax credit, in such manner as may be prescribed."

Rule 39(1)(i) — the ITC on account of integrated tax shall be distributed as ITC of integrated tax to every recipient.

Rule 39(1)(j) — the ITC on account of central tax and State tax or Union territory tax shall —

• (i) in respect of a recipient located in the same State or UT in which the ISD is located, be distributed as ITC of central tax and State tax or UT tax respectively; and
• (ii) in respect of a recipient located in a State or UT other than that of the ISD, be distributed as integrated tax, and "the amount to be so distributed shall be equal to the aggregate of the amount of ITC of central tax and State tax or Union territory tax that qualifies for distribution to such recipient."

Rule 39(1)(h) — the credit on account of central tax, State tax, UT tax and integrated tax shall be distributed separately in accordance with the attribution clauses.

The three outcomes

The Handbook's summary of the same rule, from the FAQs:

"(a) Central tax as central tax (if the recipient and ISD are located in the same State) and as integrated tax (if the recipient and ISD are located in different States). (b) SGST or UTGST as SGST or UTGST (if the recipient and ISD are located in the same State or union territory) and as integrated tax (if the recipient and ISD are located in different States). In case of distribution of central/ state tax as integrated tax, it should be ensured that the amount distributed equals the amount of credit of central and state tax put together."

Note the direction of travel. Credit only ever merges into IGST; it never splits out of IGST into CGST and SGST. An ISD holding IGST credit cannot hand a same-State branch a CGST/SGST pair — the branch receives IGST and uses it under the ordinary utilisation order.

The SEZ rule

The Handbook adds a note that is easy to miss and expensive to get wrong:

"In a case where the receiving unit is located in SEZ, then distribution of ITC out of IGST/CGST/SGST/UTGST will be distributed as IGST only irrespective of the SEZ State code."

So the ordinary same-State test does not apply to an SEZ recipient. Even where the SEZ unit carries the same State code as the ISD, the distribution goes out as IGST. That follows from the treatment of a supply to an SEZ unit or developer as an inter-State supply under section 7(5) of the IGST Act.

The reconciliation quirk

This is the consequence that causes the most confusion when a GSTR-6 summary is first reviewed, and the Handbook states it plainly:

"Total credit available (IGST+CGST+SGST) for distribution must be equal to total credit distributed (IGST+CGST+SGST), though the amounts of individual taxes may not tally."

Why the heads move. Suppose an ISD in Maharashtra holds ₹1,00,000 CGST and ₹1,00,000 SGST, distributable 40% to Mumbai and 60% to three other States.

• Mumbai (same State): ₹40,000 CGST + ₹40,000 SGST.
• The other States: ₹60,000 CGST + ₹60,000 SGST merge into ₹1,20,000 IGST.

Total out: ₹2,00,000 — exactly what came in. But the heads have changed: CGST fell from ₹1,00,000 to ₹40,000, SGST likewise, and IGST appeared from nowhere at ₹1,20,000.

The rule to apply when reviewing a return is therefore the sum, not the columns. Anyone reconciling head-wise between Table 4 (available) and Tables 5 and 8 (distributed) will find a mismatch that is not an error.

Two consequences for the recipient branch

First, a branch outside the ISD's State receives IGST, which under section 49(5) and the utilisation order in section 49A/49B is set off against IGST first, then CGST, then SGST/UTGST. That is generally helpful — IGST credit is the most flexible head.

Second, a branch in the ISD's own State receives a CGST/SGST pair, which is less flexible: SGST credit cannot be used against CGST liability and vice versa. A business with a large same-State branch and a persistent imbalance between its CGST and SGST liabilities should expect that pattern to persist through the ISD distribution — the mechanism preserves the heads, it does not optimise them.

And the ISD cannot choose. The conversion is prescribed by rule 39(1)(i) and (j); it is not an election.

Key takeaways

• IGST in, IGST out — always, to every recipient.
• CGST and SGST/UTGST stay as themselves for a recipient in the ISD's own State or UT.
• For a recipient elsewhere, CGST and SGST/UTGST merge into a single IGST amount equal to their aggregate.
• Credit never splits out of IGST back into CGST and SGST.
• An SEZ recipient always receives IGST, whatever its State code.
• Total in must equal total out each month; the individual heads will not tally, and that is by design.
• The conversion is prescribed, not elective — rule 39(1)(i) and (j).

Read next

• Rule 39: The Turnover Formula and the Relevant Period
• GSTR-6 and GSTR-6A: The Tables, and the Place-of-Supply Trap
• Eligible and Ineligible ITC: Why an ISD Distributes Both

Disclaimer: Positions stated as on 5 September 2026, based on section 20(3) of the CGST Act, 2017 and rule 39(1)(h), (i) and (j) of the CGST Rules, 2017, as reproduced in the ICAI Handbook on Input Service Distributor under GST (2nd edition, September 2025).