The Goods and Services Tax (GST) in India is a comprehensive, multi-stage, destination-based tax that has replaced multiple indirect taxes. Understanding the difference between CGST, SGST, and IGST is fundamental for every business owner, accountant, and e-commerce seller. This guide explains each component in detail, shows how they are calculated, and helps you determine which tax applies to your transactions.

What is CGST (Central Goods and Services Tax)?

CGST is the tax levied by the Central Government of India on intra-state supply of goods and services. When a transaction occurs within the same state—for example, a seller in Maharashtra sells goods to a buyer in Maharashtra—CGST is applied along with SGST. The CGST rate is always exactly half of the total applicable GST rate. For example, if the GST rate is 18%, the CGST component would be 9%.

CGST revenue goes directly to the Central Government's consolidated fund. The tax is governed by the CGST Act, 2017, which provides rules for registration, invoicing, returns filing, refunds, and enforcement related to the central tax component.

What is SGST (State Goods and Services Tax)?

SGST is the tax levied by the State Government on intra-state supply of goods and services. It is always applied alongside CGST for transactions within the same state. Like CGST, the SGST rate is exactly half of the total GST rate. If the total GST rate is 18%, SGST would be 9%.

SGST revenue goes to the respective State Government. Each state has enacted its own SGST Act, though the provisions are largely uniform across all states. For Union Territories without a legislature, the equivalent tax is called UTGST (Union Territory GST), which functions identically to SGST.

What is IGST (Integrated Goods and Services Tax)?

IGST is the tax levied by the Central Government on inter-state supply of goods and services. When a transaction crosses state boundaries—for example, a seller in Gujarat ships goods to a buyer in Karnataka—IGST is applied instead of CGST+SGST. The IGST rate equals the full GST rate (e.g., 18% IGST if the GST rate is 18%).

IGST is also applicable on imports into India and certain specified supplies. The IGST revenue is shared between the Central and State Governments based on a formula determined by the GST Council. This mechanism ensures that the destination state receives its fair share of tax revenue.

How to Determine Which Tax Applies

The "Place of Supply" rules under Sections 10-14 of the IGST Act determine which tax component applies:

• Same State (Intra-State): If the supplier's location and the place of supply are in the same state, apply CGST + SGST (each at half the GST rate).
• Different States (Inter-State): If the supplier's location and the place of supply are in different states, apply IGST (at the full GST rate).
• Imports: All imports are treated as inter-state supplies, so apply IGST.
• Exports: Exports can be zero-rated (no tax) or taxed with IGST (refundable).

GST Calculation Examples

Example 1: Intra-State Sale (CGST + SGST)

A seller in Delhi sells a laptop worth ₹50,000 to a buyer in Delhi. GST rate: 18%.

• Taxable Value: ₹50,000
• CGST (9%): ₹4,500
• SGST (9%): ₹4,500
• Total Tax: ₹9,000
• Invoice Total: ₹59,000

Example 2: Inter-State Sale (IGST)

A seller in Gujarat sells the same laptop worth ₹50,000 to a buyer in Maharashtra. GST rate: 18%.

• Taxable Value: ₹50,000
• IGST (18%): ₹9,000
• Total Tax: ₹9,000
• Invoice Total: ₹59,000

Note: The total tax amount is the same in both cases—only the classification and destination of the revenue differ.

Input Tax Credit (ITC) Across Tax Types

Understanding ITC flow is crucial for managing your tax liability:

• CGST credit can be used to offset CGST liability first, then IGST liability. It cannot be used against SGST.
• SGST credit can be used to offset SGST liability first, then IGST liability. It cannot be used against CGST.
• IGST credit can be used to offset IGST liability first, then CGST, then SGST. It is the most flexible credit type.

Using Our GST Calculator

Our free online GST Calculator automatically handles all CGST, SGST, and IGST calculations. Simply enter the taxable value, select the applicable GST rate, and specify whether the transaction is intra-state or inter-state. The tool instantly shows the tax breakdown and total invoice amount. You can also perform reverse calculations—enter the GST-inclusive price to extract the base price and tax components.

Frequently Asked Questions

Can CGST and IGST apply on the same invoice?

No. A single supply can only attract either CGST+SGST or IGST—never both. However, if an invoice contains multiple items shipped to different states, separate invoices should be raised for each place of supply.

What happens if I charge the wrong tax type?

If you incorrectly charge CGST+SGST instead of IGST (or vice versa), you may face issues during return filing. The buyer may not be able to claim ITC correctly. Issue a credit note for the incorrect invoice and raise a fresh invoice with the correct tax type.