CGST, SGST, and IGST Explained: Tax Allocation & Input Credit Rules
A comprehensive guide to India's dual GST structure: understanding when CGST + SGST applies vs IGST, determining the place of supply, and the exact order for setting off Input Tax Credit.
India’s Goods and Services Tax operates under a "dual GST" framework. Because both the Union Government and individual State Governments possess constitutional powers to levy taxes on domestic consumption, tax collection is bifurcated into distinct components: CGST, SGST, and IGST.
While the total percentage rate charged to the end buyer remains identical regardless of geography, the correct legal allocation between these components is paramount. Misallocating an intra-state supply as an inter-state supply (or vice versa) can result in blocked input tax credits, penalties under Section 77 of the CGST Act, and tedious refund applications.
This guide demystifies the roles of CGST, SGST, and IGST, provides clear rules for determining the place of supply, and illustrates how input tax credits are legally offset in your periodic returns.
1. Defining the Three Core GST Components
Central Goods and Services Tax (CGST): Levied by the Union Government on intra-state supplies of taxable goods and services. Revenue flows entirely to the Central exchequer.
State Goods and Services Tax (SGST) / Union Territory GST (UTGST): Levied by the respective State or Union Territory Government on the same intra-state supply. Revenue flows to the consuming State.
Integrated Goods and Services Tax (IGST): Levied by the Central Government on all inter-state supplies, cross-border imports, and supplies to or from Special Economic Zones (SEZs). The proceeds are apportioned between the Centre and the destination State according to constitutional formulas.
2. The 50:50 Intra-State Rule
Whenever a sale occurs within a single state boundary (for example, from a vendor in Bengaluru to a customer in Mysuru, Karnataka), the total tax is split equally down the middle between CGST and SGST:
• If the item attracts 5% GST, the invoice displays 2.5% CGST and 2.5% SGST.
• If the item attracts 18% GST, the invoice displays 9% CGST and 9% SGST.
• If the item attracts 40% GST (under GST 2.0), the invoice displays 20% CGST and 20% SGST.
If the same Bengaluru vendor ships goods to a customer in Chennai (Tamil Nadu), the entire rate is billed as IGST (5%, 18%, or 40%), with no separate CGST or SGST lines.
3. Input Tax Credit (ITC) Utilization Hierarchy (Section 49)
Businesses accumulate input tax credits on their purchases. When offsetting these credits against output tax liabilities on monthly GSTR-3B filings, the GST law enforces a strict chronological priority sequence under Section 49 and 49A:
Order 1: IGST credit must be utilized first to settle output IGST liability. Any balance IGST credit can be set off against CGST and SGST liabilities in any order and proportion.
Order 2: Only after IGST credit is completely exhausted can a business use CGST credit (first against CGST liability, then against IGST liability). CGST credit can NEVER be used to pay SGST liability.
Order 3: SGST credit can only be utilized after IGST credit is exhausted (first against SGST liability, then against IGST liability). SGST credit can NEVER be used to pay CGST liability.
| Input Tax Credit Type | Priority 1 (Must Use First) | Priority 2 (Next Balance) | Prohibited Offset |
|---|---|---|---|
| IGST Credit | Output IGST | Output CGST or SGST (any ratio) | None |
| CGST Credit | Output CGST | Output IGST | CANNOT offset Output SGST |
| SGST Credit | Output SGST | Output IGST | CANNOT offset Output CGST |
4. Practical Pitfall: What If You Pay Under the Wrong Head?
If a supplier incorrectly bills and pays CGST + SGST instead of IGST, they cannot simply request an internal adjustment. Under Section 77 of the CGST Act, the taxpayer must pay the correct tax (IGST) along with interest, and apply for a refund of the erroneously paid CGST and SGST.
Always inspect the buyer's GSTIN prefix (the first two digits represent the State Code, such as 27 for Maharashtra, 29 for Karnataka, 07 for Delhi) to verify intra-state versus inter-state status prior to invoice generation.
Frequently Asked Questions
Can CGST credit be cross-utilized to pay off SGST dues?
No. The law strictly prohibits cross-utilization between CGST and SGST credits under any circumstance. CGST funds belong to the Union Government, while SGST belongs to the State Government.
What happens to GST when selling to a SEZ (Special Economic Zone) unit within the same state?
Supplies to SEZ units or developers are legally deemed as inter-state supplies under Section 7(5)(b) of the IGST Act, even if both the seller and the SEZ reside in the exact same city. They must be invoiced under IGST (or zero-rated under Letter of Undertaking / LUT).
Summary & Best Practices
Mastering the distinction between CGST, SGST, and IGST is crucial for every accounting department in India. Correct tax assignment ensures compliance and protects your clients from frozen tax credits.
The UtilityKit GST Calculator automatically generates the exact CGST, SGST, and IGST splits based on your selected rate.
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