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Place of supply errors do not announce themselves. A transaction booked as intra-state when it is inter-state looks identical in the ERP until GSTR-2B arrives and the buyer finds CGST credit instead of IGST credit — which cannot offset the IGST liability they are expecting. By then, both parties have filed, and correction requires credit notes and revised returns.
What Determines IGST vs CGST/SGST
The foundational rule for igst cgst sgst reconciliation india is the place of supply determination:
- Inter-state supply: Supplier state differs from buyer state (or it is an import/export) — IGST applies.
- Intra-state supply: Supplier and buyer are in the same state — CGST + SGST applies.
- Union territory supply: CGST + UTGST applies instead of CGST + SGST.
For services, the place of supply defaults to the recipient’s location. For goods, it is the location to which delivery is made. E-commerce supplies follow the destination state rule regardless of warehouse location.
The GSTR-1 vs GSTR-3B reconciliation process is where tax head errors typically surface first: GSTR-1 shows IGST on a supply, but GSTR-3B shows CGST+SGST in the ledger because the accounts team corrected the tax locally without amending the invoice.
The Comparison Table Every Multi-State Finance Team Needs
| Aspect | IGST | CGST | SGST/UTGST |
|---|---|---|---|
| Jurisdiction | Central + State (inter-state) | Central government | State government |
| Applicable supply type | Inter-state, imports, exports | Intra-state | Intra-state (or UTGST for UTs) |
| ITC offset sequence (first → then) | IGST → CGST → SGST | CGST → IGST | SGST → IGST |
| GSTR-3B reporting table | Table 3.1(a) for outward; Table 4 for ITC | Table 3.1(a); Table 4 | Table 3.1(a); Table 4 |
| Cross-utilisation with other head | Yes (can offset all three) | Only CGST and IGST | Only SGST and IGST |
| Portal account | IGST head in electronic ledger | CGST head | SGST/UTGST head |
Why Multi-GSTIN Businesses Face the Hardest Reconciliation
A company with GST registrations in Maharashtra, Karnataka, Tamil Nadu, Delhi, and Gujarat maintains five separate GSTR-3B filings. An inter-state stock transfer from Maharashtra to Karnataka is a supply — the Maharashtra GSTIN charges IGST, the Karnataka GSTIN claims it as ITC. If the Maharashtra entity records it as an intra-state transfer and applies CGST+SGST, the Karnataka entity finds CGST credit in GSTR-2B for an IGST liability — an uncorrectable offset until a credit note is raised and a fresh IGST invoice is issued.
This cross-GSTIN reconciliation is best handled by reviewing the GSTR-2B reconciliation for each destination GSTIN monthly, verifying that the tax head on every ITC credit matches the expected inter- or intra-state classification. The GST portal maintains separate electronic ledger accounts for each head under each GSTIN.
ITC Set-Off Hierarchy: Mandatory, Not Optional
The Finance Act 2019 amended the GST Act to make the ITC set-off sequence mandatory:
- IGST ITC is used first to pay IGST liability. Remaining IGST ITC offsets CGST, then SGST.
- CGST ITC pays CGST first, then IGST.
- SGST ITC pays SGST first, then IGST.
- CGST ITC cannot offset SGST; SGST ITC cannot offset CGST.
The GSTR-9 annual return reconciliation process for multi-GSTIN businesses should verify that this sequence was followed in every GSTR-3B filing across all GSTINs for the year. Violations discovered in GSTR-9 require additional tax payment with 18% interest.
Common Booking Errors and Their Downstream Impact
Error 1 — Wrong state determination for B2B services: An IT firm in Bengaluru provides consultancy to a client’s head office in Mumbai. The invoice is raised to the Mumbai office — IGST applies. If the accounts team sees a Bengaluru-based relationship manager as the point of contact and books it as CGST+SGST, the Mumbai buyer receives the wrong credit and cannot offset their IGST output tax with it.
Error 2 — CGST ITC used against SGST liability: Some older ERP configurations allow free-form offset entries. A finance executive manually applies CGST ITC to clear SGST liability — a disallowed set-off. This does not raise an immediate portal error but surfaces as a discrepancy in GSTR-9 when annual reconciliation compares the utilisation register to the legal offset rules.
Reconciliation software India finance teams deploy for multi-GSTIN businesses typically enforces offset rules at the data layer, flagging any proposed utilisation that violates the Finance Act 2019 sequence before GSTR-3B is filed.
Correction Protocol When Tax Head Is Wrong
When a tax head error is found post-filing, the correction path is:
- Supplier issues a credit note (Section 34) for the original incorrectly taxed invoice.
- Supplier raises a fresh invoice with the correct tax head and rate.
- Both are reported in the next month’s GSTR-1.
- The buyer’s GSTR-2B in the next month shows the credit note (reversing the wrong credit) and the new invoice (creating the correct credit).
If the error spans a financial year boundary, the credit note time limit (September 30 of the following FY or the annual return filing date, whichever is earlier) constrains how long correction remains possible.
GST reconciliation software built for multi-state operations flags tax head mismatches at invoice import, reducing the correction backlog before it accumulates across months.