Interstate vs Intrastate GST Invoice: CGST, SGST, IGST Explained Simply
The difference between an interstate and an intrastate GST invoice depends strictly on the supplier's location and the official Place of Supply defined under the IGST Act. When the supplier and the customer's place of supply are in the same state, the transaction is intrastate and attracts equal splits of CGST and SGST; when they are in different states, the supply is interstate and attracts Integrated GST (IGST) at the full combined tax rate.
For Indian business owners, selecting the wrong tax structure on an invoice is among the most common and costly indirect tax errors. Charging CGST and SGST when shipping goods across state lines—or billing IGST for a local customer—violates statutory tax rules, complicates GSTR-1 filings, and prevents corporate buyers from claiming Input Tax Credit (ITC). To streamline your tax invoicing, review Udyog pricing plans.
In this guide, we demystify the legal definitions under Section 7 and Section 8 of the IGST Act, break down Place of Supply determination for goods and services, explain how to rectify incorrect tax payments under Section 77, and show how automated billing tools eliminate manual tax selection errors.
What is an intrastate supply and how are CGST and SGST calculated?
Under Section 8 of the Integrated Goods and Services Tax (IGST) Act, 2017, an intrastate supply occurs when the location of the supplier and the Place of Supply of the goods or services are within the same State or Union Territory. In this scenario, indirect tax is divided equally between the Central Government and the State Government.
For example, if a textile merchant in Surat (Gujarat, State Code 24) sells cotton fabric worth ₹1,00,000 to a garment retailer in Ahmedabad (Gujarat, State Code 24) at an 18% GST rate, the invoice must reflect:
- •Taxable Value of Supply: ₹1,00,000.00
- •Central GST (CGST @ 9%): ₹9,000.00 (Credited to the Central Government treasury)
- •State GST (SGST @ 9%): ₹9,000.00 (Credited to the Government of Gujarat)
- •Total Invoice Value: ₹1,18,000.00
What is an interstate supply and when does IGST apply?
Under Section 7 of the IGST Act, an interstate supply occurs when the location of the supplier and the Place of Supply are in two different States, two different Union Territories, or a State and a Union Territory. Furthermore, all import supplies, export supplies, and transactions involving Special Economic Zone (SEZ) developers or units are legally deemed interstate supplies regardless of geographic proximity.
If the same Surat manufacturer sells ₹1,00,000 worth of fabric to a boutique in Mumbai (Maharashtra, State Code 27), the transaction crosses state borders. The invoice must not show CGST or SGST; instead, it must bill the full 18% tax as Integrated GST (IGST):
- •Taxable Value of Supply: ₹1,00,000.00
- •Integrated GST (IGST @ 18%): ₹18,000.00
- •Total Invoice Value: ₹1,18,000.00
| Transaction Parameter | Intrastate Supply Invoice | Interstate Supply Invoice | Legal Governing Provision |
|---|---|---|---|
| Supplier Location vs Place of Supply | Within the same State / UT | In two different States / UTs | Section 7 vs Section 8, IGST Act |
| Taxes Charged on Invoice | CGST + SGST (or UTGST) | IGST (Integrated Tax) | Section 9 CGST Act / Section 5 IGST Act |
| Tax Rate Split | Exact 50% / 50% equal split | Full 100% combined tax rate | CBIC Rate Notifications |
| Export of Goods / Services | Not applicable | Always Interstate (IGST/LUT) | Section 7(5)(a) of IGST Act |
| Supply to SEZ Unit / Developer | Never Intrastate (Even if adjacent) | Always Interstate (IGST/LUT) | Section 7(5)(b) of IGST Act |
| State Code Rule | Supplier Code == Recipient Code | Supplier Code != Recipient Code | Rule 46(f) of CGST Rules |
How do Place of Supply rules determine tax classification?
The critical factor in tax determination is not the customer's billing address, but the official 'Place of Supply'. For tangible goods (governed by Section 10 of the IGST Act), the place of supply is generally where the movement of goods terminates for delivery to the recipient.
For services (governed by Section 12 and Section 13), place of supply rules vary by category: for registered B2B clients, it is the location of the recipient; for immovable property services (like hotel accommodation or warehouse leasing), it is the physical location of the property; and for passenger transport or event admission, it is where the event or journey occurs. Learn more about statutory requirements in our guide on GST invoice rules in 2026.
Crucial Tax Rule for Bill-To / Ship-To Models
Under Section 10(1)(b) of the IGST Act, if a buyer in Delhi instructs you (in Haryana) to ship goods directly to their factory branch in Rajasthan, the transaction between you and the Delhi buyer is interstate (IGST charged to Delhi), even though goods were physically delivered to Rajasthan.
What happens if you charge the wrong tax on an invoice?
If you inadvertently charge CGST and SGST instead of IGST (or vice versa), you cannot simply adjust the amounts internally on your next return. Under Section 77 of the CGST Act and Section 19 of the IGST Act:
- 1Pay the Correct Tax: You must deposit the correct tax (e.g., IGST) into the government treasury with your subsequent GSTR-3B return.
- 2No Interest Liability: Because the incorrect payment occurred under a bona fide classification mistake, no interest is payable under Section 50 on the delayed correct tax.
- 3Claim a Refund for Incorrect Tax: You must file a formal GST RFD-01 refund application under Section 54 to recover the CGST and SGST wrongly paid.
- 4Buyer ITC Complications: Until the error is rectified via an amended GSTR-1, your buyer cannot claim input tax credit because their GSTR-2B will show mismatched tax ledgers.
Why Indian businesses rely on Udyog to prevent tax classification errors
Manual selection of CGST, SGST, or IGST in spreadsheets leads to frequent clerical errors. Udyog automates Place of Supply logic completely.
- •Automatic State Code Detection: The moment you enter or dictate a customer's GSTIN, Udyog extracts the first 2 digits (e.g., '27' for Maharashtra) and compares it to your registered warehouse state.
- •Smart Tax Routing: If state codes match, Udyog splits taxes into CGST+SGST automatically; if they differ, it applies IGST with zero manual intervention.
- •SEZ and Export Handling: Flag clients as Special Economic Zone units with a single toggle; Udyog applies interstate tax or LUT bond declarations automatically.
- •One-Click WhatsApp Sharing: Send compliant PDF bills with transparent tax breakdowns and instant UPI payment links directly to customer WhatsApp accounts.
Never make a CGST/SGST or IGST tax mistake again. Automate Place of Supply rules, HSN assignment, and GST billing with Udyog.
Start 14-Day Free Trial →Frequently asked questions
Quick answers to common questions.
What is the primary difference between intrastate and interstate GST supplies?
An intrastate supply occurs when the supplier and place of supply are in the same state, attracting equal CGST and SGST splits. An interstate supply occurs across state borders, attracting single Integrated GST (IGST).
Can a business charge CGST and SGST on goods delivered to another state?
No, delivering goods across state boundaries constitutes an interstate supply under Section 7 of the IGST Act, requiring Integrated GST (IGST). Charging CGST and SGST on interstate sales is legally invalid.
What is the procedure if a seller mistakenly deposits CGST+SGST instead of IGST?
Under Section 77 of the CGST Act, the seller must pay the correct IGST amount without interest and file a formal refund application (GST RFD-01) to recover the wrongly deposited CGST and SGST.
How does Place of Supply determine tax for services provided to corporate clients?
For registered B2B clients under Section 12 of the IGST Act, the Place of Supply is the registered location of the recipient, which determines whether the service invoice attracts CGST+SGST or IGST.
Does Udyog detect interstate and intrastate taxes automatically?
Yes, Udyog compares the 2-digit state prefix codes of the supplier and customer GSTINs automatically, correctly applying CGST+SGST or IGST without requiring manual tax selection.