What is CGST, SGST, and IGST? A Simple Guide

When India introduced the Goods and Services Tax (GST) on July 1, 2017, it replaced a complex web of indirect taxes (like VAT, Service Tax, Excise Duty, and Octroi) with a single, unified tax system. The motto was "One Nation, One Tax."

However, because India operates on a federal structure where both the Central and State governments have the power to levy and collect taxes, a "Dual GST" model was adopted. This is why you see GST split into CGST, SGST, and IGST on your bills and invoices.

Understanding when and how to apply these three components is critical for any business owner issuing invoices. Let's break them down simply.

1. CGST (Central Goods and Services Tax)

CGST stands for Central Goods and Services Tax. It is the portion of the tax that is collected by the Central Government of India.

CGST is applicable on intrastate supplies. Intrastate means the sale of goods or services happens within the same state. For example, if a supplier in Bangalore (Karnataka) sells goods to a buyer in Mysore (Karnataka), it is an intrastate sale.

If the total GST rate for the product is 18%, the Central Government will collect 9% as CGST.

2. SGST (State Goods and Services Tax)

SGST stands for State Goods and Services Tax. It is the portion of the tax that is collected by the State Government where the transaction takes place.

Like CGST, SGST is also applicable only on intrastate supplies (sales within the same state). In every intrastate transaction, CGST and SGST are applied together, effectively splitting the total tax revenue equally between the Centre and the State.

Going back to our previous example: A supplier in Bangalore sells a laptop to a buyer in Mysore. The laptop is in the 18% GST slab.

• 9% will go to the Centre as CGST.
• 9% will go to the Karnataka State Government as SGST.

Note: In Union Territories (like Delhi, Chandigarh, or Andaman and Nicobar Islands), SGST is replaced by UGST/UTGST (Union Territory Goods and Services Tax).

3. IGST (Integrated Goods and Services Tax)

IGST stands for Integrated Goods and Services Tax. Unlike CGST and SGST, IGST is collected entirely by the Central Government.

IGST is applicable on interstate supplies. Interstate means the sale of goods or services happens between two different states. It is also applicable on imports into India and exports from India.

For example, if a manufacturer in Mumbai (Maharashtra) sells goods to a distributor in Ahmedabad (Gujarat), it is an interstate sale. If the applicable GST rate is 18%, the entire 18% will be charged as IGST.

The Central Government collects this IGST and later apportions the state's share to the destination state (Gujarat, in this case, because GST is a destination-based consumption tax).

Summary: When to apply what?

To summarize the rules for your invoicing:

Type of Transaction	Where the sale happens	Taxes to Apply	Example (18% Slab)
Intrastate Sale	Within the same state	CGST + SGST	9% CGST + 9% SGST
Interstate Sale	Between different states	IGST only	18% IGST
Import / Export	Outside India	IGST only	18% IGST

How to Handle This on Your Invoices

If you are manually calculating these taxes, it can be tedious to determine whether to apply CGST/SGST or IGST, and then calculate the math. Mistakes in applying the wrong tax head can lead to compliance issues during your monthly GSTR filings.

This is where automation helps. By using a tool like the JusBill GST Invoice Generator, you don't need to do the math manually.

When you enter the seller's state and the buyer's state in our tool, the system automatically detects whether the transaction is intrastate or interstate, and automatically splits your total GST rate into the correct CGST/SGST or IGST columns on your final PDF invoice.

Conclusion

The dual structure of CGST, SGST, and IGST ensures that tax revenues are distributed fairly between the Central and State governments while maintaining a unified tax rate across the country for consumers. As a business owner, as long as you accurately record the billing address of your customers and apply the rules above, your invoicing will be 100% compliant with Indian tax laws.