GST Invoice Format in India: Complete Guide to CGST, SGST and IGST

Direct Answer: What a GST Invoice Must Contain

A GST-compliant tax invoice must include the supplier's GSTIN, invoice number, date, HSN/SAC code, taxable value, and the applicable tax, CGST and SGST for intra-state sales, or IGST for inter-state sales. Every GST-registered business with annual turnover above Rs. 40 lakh (Rs. 20 lakh for service providers and special category states) is required to issue a tax invoice for every taxable supply. Failure to do so attracts penalties under the CGST Act, 2017.

What Is a GST Invoice?

A GST invoice (formally called a 'Tax Invoice' under the CGST Act, 2017) is a document issued by a registered supplier when goods or services are sold. It serves three purposes simultaneously: it is a commercial record of the transaction, a legal document that entitles the recipient to claim Input Tax Credit (ITC), and a data source that feeds into the supplier's GSTR-1 and the buyer's GSTR-2B auto-population on the GST portal.

Without a properly formatted tax invoice, the buyer cannot claim ITC, making invoice compliance one of the most commercially significant obligations under GST. The format is governed by Rule 46 of the CGST Rules, 2017, and mandatory fields are prescribed under Section 31 of the CGST Act.

Businesses registered under the Composition Scheme or supplying exempt goods/services must issue a 'Bill of Supply' instead of a tax invoice. A Bill of Supply cannot show tax separately and the buyer cannot claim ITC from it.

CGST, SGST and IGST: Which Tax Applies on Your Invoice?

The three taxes on a GST invoice are not interchangeable. The correct tax depends entirely on whether the supply is intra-state (within the same state) or inter-state (across states or union territories). Getting this wrong is one of the most common and costly GST errors.

CGST (Central GST) is collected by the Central Government on intra-state supplies and always appears alongside SGST at half the total GST rate. For example, 18% GST equals 9% CGST plus 9% SGST. SGST (State GST) mirrors the CGST rate and revenue stays with the state of consumption. IGST (Integrated GST) applies on inter-state supplies, imports and exports at the full combined rate, collected by the Centre and distributed to the destination state.

A practical rule: if the supplier's state code (first two digits of GSTIN) and the place of supply are the same, charge CGST and SGST. If they differ, charge IGST. For exports, the invoice should be marked 'Supply meant for Export on Payment of IGST' or 'Supply meant for Export Under Bond/LUT Without Payment of IGST.'

Who Must Issue a GST Tax Invoice?

Every GST-registered supplier is required to issue a tax invoice under Section 31 of the CGST Act.

From August 1, 2023, businesses with aggregate annual turnover above Rs. 5 crore must generate invoices on the Invoice Registration Portal (IRP). The IRP returns a signed JSON with an Invoice Reference Number (IRN) and QR code, both of which must be printed on the physical invoice. Without an IRN, the invoice is legally invalid for ITC purposes.

• Regular taxpayers: mandatory for every taxable supply regardless of amount.
• Supply to unregistered persons: a tax invoice is still required; the supplier must self-declare the place of supply.
• Value below Rs. 200: if the recipient is unregistered and does not require an invoice, a consolidated invoice covering all such supplies within a day may be issued.
• Continuous supply of services: invoice must be issued on or before each due date of payment as per the contract, or on receipt of payment, whichever is earlier.
• E-commerce operators: must issue invoices on behalf of unregistered suppliers listed on their platform under TCS provisions.

Mandatory Fields in a GST Invoice (Rule 46, CGST Rules 2017)

Rule 46 of the CGST Rules, 2017 lists every field that must appear on a tax invoice. Missing even one mandatory field can result in the buyer's ITC claim being denied, and can attract a penalty of Rs. 10,000 per invoice or the amount of tax evaded, whichever is higher, under Section 122 of the CGST Act.

The full list of mandatory fields includes: supplier name, address and GSTIN; a consecutive unique invoice number (max 16 characters); invoice date; recipient name, address and GSTIN (for B2B supplies); place of supply; HSN or SAC code; description of goods or services; quantity and unit (for goods); taxable value; applicable tax rate and amount (CGST plus SGST, or IGST); total invoice value in figures and in words; a reverse charge indicator; and signature or digital signature of an authorised signatory. For e-invoicing taxpayers, the IRN and QR code from the IRP are additionally mandatory.

GST Invoice Format: Worked Example with Real Rupee Numbers

Consider an intra-state supply by Aarav Tech Solutions Pvt. Ltd. (GSTIN: 27AABCA1234F1Z5, Maharashtra) to Meera Retail Pvt. Ltd. (GSTIN: 27BBBCM5678G1ZX, Maharashtra) on 15 June 2026. Because both parties are in Maharashtra, CGST and SGST at 9% each apply on the 18% GST rate slab.

The invoice covers three line items: Software Development Services at Rs. 85,000 (SAC 998314), Annual Maintenance Contract at Rs. 30,000 (12 months x Rs. 2,500, SAC 998313), and Cloud Hosting Setup at Rs. 5,000 (SAC 998315). Total taxable value = Rs. 1,20,000.

CGST at 9% = Rs. 10,800. SGST at 9% = Rs. 10,800. Total tax = Rs. 21,600. Total invoice value = Rs. 1,41,600 (Rupees One Lakh Forty One Thousand Six Hundred Only). If the same supply were made to a Delhi buyer, IGST at 18% = Rs. 21,600 would appear instead, and the total payable would remain identical. You can generate this exact format using our GST invoice generator.

How to Create a GST Invoice: Step-by-Step

Creating a compliant GST tax invoice involves seven steps, each with a specific compliance implication.

• Verify registration status: confirm your GSTIN is active on the GST portal. Your GSTIN's first two digits are your state code, used to determine CGST+SGST vs IGST.
• Determine the place of supply: for goods, it is where delivery occurs; for services, it defaults to the recipient's registered address.
• Assign a unique invoice number: consecutive, alphanumeric, max 16 characters, unique within the financial year (April to March).
• Identify the correct HSN/SAC code: 4-digit for turnover up to Rs. 5 crore, 6-digit for above Rs. 5 crore.
• Calculate taxable value and GST: apply any discounts, then multiply taxable value by the applicable GST rate and split into CGST/SGST or show as IGST.
• Check e-invoicing requirement: if turnover exceeded Rs. 5 crore in any preceding year, upload to the IRP and print the IRN and QR code on the invoice.
• Issue and retain copies: provide the original to the buyer and retain a duplicate for 72 months (6 years) from the annual return due date.

GST Invoice for Services vs Goods: Key Differences

While most fields are common, there are format differences when invoicing for services versus goods. For goods, the HSN code (Schedule I, CGST Act) applies and the quantity field with unit of measurement is mandatory. Time of supply is the earlier of: date of removal/delivery or date of payment receipt. An e-way bill is required for inter-state movement above Rs. 50,000.

For services, the SAC code (Chapter 99) applies and the quantity field is not applicable. Time of supply is the earlier of: date of invoice, date of payment, or 30 days from completion of service. E-way bills are not required for services (except pipeline transport). Place of supply defaults to the recipient's registered location.

GST Invoice Deadlines and Time Limits

The CGST Act specifies strict deadlines for issuing tax invoices. Missing these affects both the supplier's tax liability date and the buyer's ITC eligibility. For goods (non-continuous supply), invoices must be issued before or at the time of removal/delivery. For services, invoices must be issued within 30 days of supply (45 days for banks and NBFCs). For continuous supply of services, on or before each payment due date or on receipt of payment, whichever is earlier.

From FY 2022-23 onwards (Finance Act 2022 amendment), recipients can claim ITC only until 30th November following the end of the financial year in which supply was received, or the date of filing GSTR-9, whichever comes first. This makes timely invoicing directly important to the buyer's cash flow.

Common GST Invoice Mistakes and How to Avoid Them

GST officers frequently flag the following errors during scrutiny assessments. Many result in ITC reversals for the buyer and penalty notices for the supplier.

• Wrong tax type (CGST/SGST charged instead of IGST): always verify the buyer's GSTIN prefix against the delivery state. Issue a credit note and reissue with the correct tax head to correct errors.
• Incorrect or missing HSN/SAC code: verify codes on the official GST rate schedule at cbic-gst.gov.in before invoicing a new product or service.
• Non-sequential invoice numbering: always cancel, never delete, draft invoices to avoid gaps that suggest suppression of supply.
• GSTIN mismatch: a single digit error in the buyer's GSTIN prevents GSTR-2B auto-population and blocks their ITC claim.
• Missing 'Reverse Charge' declaration: for notified services (legal, GTA, import of services), the invoice must state 'Reverse Charge Applicable: Yes' even when the tax amount is zero.
• Signature missing: an invoice without an authorised signatory's signature or DSC is technically incomplete under Rule 46(r).
• Rounding errors: round only the final total invoice value, not individual line items, to avoid cumulative discrepancies.

Credit Notes and Debit Notes Under GST

A credit note is issued by the supplier when the original invoice overstates the taxable value or tax amount (for example, due to goods returns, price revision, or invoice errors). A debit note is issued when the original invoice understates the value. Both documents must reference the original invoice number and date, and must be reported in GSTR-1.

Credit notes must be issued by November 30 following the financial year of the original supply, or the date of filing GSTR-9, whichever comes first. There is no statutory time limit on issuing debit notes, since they result in additional tax liability. Use our general bill generator for non-GST commercial documentation alongside your tax invoices.

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