GST on every sale or purchase in India is split one of two ways depending on where the buyer is located, and in a small set of notified cases the buyer — not the supplier — is the one who must pay it directly to the government. Use the calculator below to see the CGST/SGST/IGST split for any amount, and check whether reverse charge (RCM) shifts the liability to you.
Reverse charge only applies to specific notified goods/services (e.g. GTA freight, sponsorship, some purchases from unregistered suppliers) — select it only if your transaction falls under a notified RCM category.
How the CGST / SGST / IGST split works
Intra-state: CGST = SGST = Rate ÷ 2 × Taxable value. Inter-state: IGST = Rate × Taxable value.
- Intra-state (buyer in the same state as the seller) — the rate splits equally into CGST (central government) and SGST (state government). An 18% rate becomes 9% CGST + 9% SGST.
- Inter-state (buyer in a different state) — the full rate is charged as one IGST, collected by the central government and apportioned to the consuming state. 18% stays 18% IGST.
The total tax collected is identical either way — only the split changes. On input tax credit, IGST credit must first be used against IGST liability, then CGST, then SGST; CGST credit can never be set off against SGST liability or vice versa.
What is reverse charge (RCM) and when does it apply?
Reverse charge shifts the liability to pay GST from the supplier to the recipient for a specific, notified list of goods and services — it is the exception, not the default. Under RCM you pay the GST directly to the government in cash through your GSTR-3B (it cannot be settled by offsetting existing input tax credit), and the supplier's invoice does not include GST at all.
- Goods Transport Agency (GTA) freight — if the GTA has not opted to pay tax under forward charge, the person liable to pay the freight (often the seller moving stock between warehouses) pays GST under RCM, commonly at 5% without ITC to the GTA.
- Sponsorship services — the recipient of a sponsorship service pays GST under RCM, not the sponsor's counterparty.
- Import of services from a supplier outside India, for business use.
- Specified purchases from unregistered suppliers — only for categories the government has explicitly notified, not general trade purchases.
Because the notified list changes over time, treat any RCM case flagged by this calculator as a starting point and confirm it against the current CBIC notification before filing.
Worked example: forward charge vs reverse charge
| Line | A: Regular purchase (forward charge) | B: GTA freight (reverse charge) |
|---|---|---|
| Taxable value | ₹10,000 | ₹5,000 |
| GST rate | 18% | 5% (RCM, no ITC to the GTA) |
| CGST | ₹900 | ₹125 |
| SGST | ₹900 | ₹125 |
| Total GST | ₹1,800 | ₹250 |
| Supplier's invoice shows | ₹11,800 (incl. GST) | ₹5,000 (no GST charged) |
| Who pays the GST | Supplier collects & remits it | You pay ₹250 directly to the government, then claim it back as ITC if eligible |
FAQ
What is the difference between CGST, SGST and IGST?
CGST and SGST are charged together on intra-state sales (buyer and seller in the same state), splitting the GST rate equally between the central and state governments. IGST is charged instead on inter-state sales, at the full combined rate, and is collected by the central government before being apportioned to the consuming state.
Does the total GST amount change between intra-state and inter-state sales?
No. The total tax is identical — only how it's split changes. An 18% sale is 9% CGST + 9% SGST intra-state, or 18% IGST inter-state.
What is reverse charge (RCM) under GST?
Reverse charge shifts the liability to pay GST from the supplier to the recipient (buyer) for specific notified goods and services — for example, goods transport agency (GTA) freight and sponsorship services. Under RCM you pay the GST directly to the government in cash rather than the supplier collecting it on the invoice.
Can I claim input tax credit (ITC) on GST paid under reverse charge?
Generally yes, if the goods or services are used for your business and you meet the standard ITC conditions. The tax must still be paid in cash first — it cannot be discharged by offsetting existing ITC balances.
Which purchases most commonly trigger reverse charge for online sellers?
The most common cases are freight paid to a goods transport agency that hasn't opted for forward charge, and sponsorship services. Reverse charge on purchases from unregistered suppliers applies only to specific notified categories, not general trade purchases — check the current CBIC notification before assuming RCM applies.