Business Software
What CGST, SGST and IGST are, how GST splits between them based on intra-state vs inter-state supply, and how to calculate each — with practical examples.
Checked against current rules for GST 2.0 rate slabs on 29 September 2026. Source: CBIC Notification No. 9/2025-Central Tax (Rate).
Every GST-registered sale in India charges tax under one of two arrangements — CGST + SGST, or IGST — never both, and never neither (except for exempt or nil-rated supplies). Which arrangement applies depends entirely on where the buyer and seller are located, not on what's being sold.
CGST is the portion of GST collected by the Central Government on an intra-state supply (a transaction where the buyer and seller are registered in the same state or union territory). It's charged alongside SGST, not instead of it — the two together make up the full GST rate on the transaction.
SGST is the matching portion collected by the state government where the supply takes place, charged at the same rate as CGST on the same intra-state transaction. (Union territories without their own legislature charge UTGST instead of SGST, functioning the same way.)
IGST applies to an inter-state supply — a transaction where the buyer and seller are registered in different states — and to imports. Instead of splitting the tax into two components, the full GST amount is charged as a single IGST line, collected by the Central Government and then apportioned to the destination state through the GST settlement mechanism.
| Supply type | Definition | Tax charged |
|---|---|---|
| Intra-state supply | Buyer's and seller's place of supply are in the same state/UT | CGST + SGST (or CGST + UTGST) |
| Inter-state supply | Buyer's and seller's place of supply are in different states/UTs, or the supply is an import/export | IGST |
"Place of supply" — not simply the seller's registered address — is the technical determinant used to classify a transaction; for most straightforward goods sales it lines up with the buyer's delivery location. Most standalone calculators, including the one below, can't determine this for you from the transaction amount alone, which is why you select intra-state or inter-state directly rather than having it inferred.
A Maharashtra-based business sells ₹10,000 worth of goods at 18% GST, charging ₹1,800 total GST either way. Here's how that ₹1,800 is charged depending on where the buyer is:
| Buyer location | Supply type | CGST | SGST | IGST | Total tax |
|---|---|---|---|---|---|
| Maharashtra (same state as seller) | Intra-state | ₹900 | ₹900 | — | ₹1,800 |
| Karnataka (different state) | Inter-state | — | — | ₹1,800 | ₹1,800 |
The relationship between CGST/SGST and IGST
IGST is always set equal to CGST + SGST combined for the same goods or service — it isn't a separate or additional tax rate. The total tax collected on a ₹10,000 sale at 18% is ₹1,800 either way; only how it's split and which government collects it changes based on whether the sale is intra-state or inter-state.
Getting CGST/SGST vs IGST wrong on an invoice isn't just a labelling issue — it affects which input tax credit a buyer can claim and can trigger compliance notices if a supply is taxed under the wrong head. Always confirm the place of supply before choosing which tax type to charge, particularly for services, where the place of supply rules can differ from a simple goods-delivery address.
For a straightforward GST calculation with the CGST/SGST/IGST split handled automatically, use the free GST calculator below — then generate a compliant invoice with the GST Invoice Generator once your numbers are confirmed.
Free GST Calculator
Calculate GST, CGST, SGST and IGST from a base amount, or reverse-calculate the base amount and GST from a GST-inclusive total — no signup required.
What is the difference between CGST, SGST and IGST?
CGST (Central GST) and SGST (State GST) are charged together, in equal halves, on an intra-state supply — a sale where the buyer and seller are in the same state. IGST (Integrated GST) is charged instead, as a single full-rate tax, on an inter-state supply — a sale between different states. A transaction is never charged all three at once.
How is GST split between CGST and SGST?
Equally. If the total GST on a transaction is 18%, an intra-state sale charges 9% CGST and 9% SGST — never a different split. The two together always equal the total GST rate.
Is IGST higher than CGST + SGST?
No. IGST is set equal to the combined CGST + SGST rate for the same goods or service — it's charged as a single line instead of two, not as an additional tax. The total tax burden on a given supply is the same whether it's taxed as CGST + SGST or as IGST; only the collection mechanism and how revenue is distributed between the Centre and the states differs.
Free GST Invoice Generator
Create a professional GST invoice online for free, with automatic CGST, SGST and IGST calculations.
Free Delivery Challan Generator
Create a professional delivery challan online for free — document the movement of goods from sender to receiver, with optional transport details, then preview, print or download it as a PDF.
GST & Tax
How to Calculate GST
GST-exclusive and GST-inclusive calculations, CGST/SGST vs IGST, and the formulas behind both — with worked examples at current GST 2.0 rates.
GST & Tax
GST Inclusive vs GST Exclusive: What's the Difference?
What GST-inclusive and GST-exclusive prices mean, how to convert between them, and when each calculation is the right one to use — with worked examples.
GST & Tax
How to Calculate GST From a Total Amount
Step-by-step reverse GST calculation: how to back-solve the base amount and GST portion from a GST-inclusive total, with worked examples at every GST 2.0 rate.
GST & Tax
What Must a GST Invoice Contain?
The mandatory particulars every GST tax invoice must show under Rule 46 of the CGST Rules — with a worked example, common mistakes, and when different invoice rules apply.