GST Invoice Format 2025–26 — Complete Guide, Mandatory Fields, B2B B2C Formats, E-Invoice, Free Excel Download

📁 Category: GST  |  🗓️ Last Updated: February 2026  |  ✍️ By: DisyTax Team  |  📖 Reading Time: ~18 Minutes

A GST invoice — formally called a Tax Invoice under GST — is far more than a billing document. Under India's Goods and Services Tax framework, it is a legally mandated document that establishes the supplier's tax liability, enables the buyer's Input Tax Credit (ITC), determines the applicable tax (CGST, SGST, or IGST) based on the place of supply, and serves as primary evidence in GST audits, notices, and litigation. Whether you are a manufacturer, wholesale trader, retailer, service provider, exporter, freelancer, e-commerce seller, composition dealer, or small business owner — understanding the correct GST invoice format, mandatory fields under Rule 46, and invoicing rules under Section 31 of the CGST Act, 2017 is absolutely non-negotiable.

This comprehensive guide covers every aspect of GST invoicing — from the basic structure and mandatory fields, to the difference between B2B and B2C invoice formats, intrastate vs interstate tax application (CGST+SGST vs IGST), e-invoice requirements, time limits, credit and debit notes, invoice cancellation, GSTR-1 reporting, common mistakes, penalties, and a free professional Excel template download with automatic tax calculations.

1. What is a GST Tax Invoice? — Definition, Legal Basis & Importance

A GST Tax Invoice is an official document issued by a registered supplier to a recipient at the time of supply of taxable goods or services. It records every transaction detail including the identities of both parties, nature of supply, quantity, taxable value, applicable GST rates (CGST, SGST, IGST, or Cess), and the resulting tax liability. It is the foundational document of the entire GST compliance ecosystem.

Under Section 31(1) of the CGST Act, 2017, every registered person supplying taxable goods must issue a tax invoice. Under Section 31(2), every registered person supplying taxable services must also issue a tax invoice. The format, content, and serial numbering of tax invoices are prescribed under Rule 46 of the CGST Rules, 2017.

Why a Proper GST Invoice Matters

• ITC Eligibility: Under Section 16(2)(aa), a buyer can claim Input Tax Credit only if the invoice is reflected in GSTR-2B. An invalid or missing invoice blocks ITC permanently.
• Tax Liability: The invoice determines when the supplier's GST liability arises (time of supply) and the amount of tax due.
• GSTR-1 Reporting: B2B invoice details must be reported in GSTR-1 at the invoice level — errors in invoicing lead to mismatches and notices.
• E-Way Bill: An e-way bill for goods movement is based on the tax invoice details — a wrong invoice invalidates the e-way bill.
• Legal Evidence: In case of GST audit, scrutiny, or litigation, the tax invoice is the primary legal document.
• Export Benefits: For exporters, the tax invoice is the basis for IGST refund or LUT-based export.

2. CGST vs SGST vs IGST — Which Tax on Which Invoice?

One of the most critical aspects of GST invoicing is correctly determining whether to charge CGST + SGST (intrastate) or IGST (interstate). Charging the wrong tax type is a serious compliance error — it can result in wrong ITC being claimed by the buyer, demand notices, and penalties.

3. Mandatory Fields in a GST Invoice — Rule 46, CGST Rules 2017

Rule 46 of the CGST Rules, 2017 prescribes the content of a tax invoice in detail. Every field is legally required — even a single missing mandatory field can make the invoice non-compliant, block ITC for the buyer, and attract penalties.

4. GST Invoice Sample Format — B2B (With IGST + CGST/SGST All Columns)

Below is a complete professional B2B Tax Invoice sample as per Rule 46 of CGST Rules, 2017 with all tax columns — CGST, SGST, and IGST. This format supports both intrastate and interstate supply. Download the Excel version using the button below.

5. Types of GST Invoices — B2B, B2C, B2CL, B2CS, Export, RCM, Composition

Type 1 — B2B Invoice (Business to Business)

Issued when a registered supplier makes a taxable supply to another GST-registered business. This is the most common invoice type for wholesale, manufacturing, and service businesses.

• Buyer's GSTIN is mandatory on the invoice
• Both supplier and buyer GSTIN must be correctly mentioned
• Full tax breakdown — CGST + SGST (intrastate) or IGST (interstate)
• HSN/SAC code is mandatory for every line item
• Buyer can claim full Input Tax Credit (ITC) subject to Section 16 conditions
• Invoice must be reported invoice-wise in Table 4A, 4B, 4C, or 6B of GSTR-1
• E-invoicing mandatory if supplier's AATO exceeds ₹5 crore
• E-way bill required for goods transport if value exceeds ₹50,000

Type 2 — B2C Invoice (Business to Consumer)

Issued when a registered supplier makes a taxable supply to an unregistered person (end consumer, individual, unregistered business).

• Buyer's GSTIN is NOT required
• Buyer cannot claim ITC on B2C purchases
• E-invoicing is currently not applicable to B2C supplies

B2CS — B2C Small Invoice

• All intrastate B2C supplies (any value)
• Interstate B2C supplies below ₹2.5 lakh (₹1 lakh effective from August 1, 2024)
• Reported as state-wise consolidated summary in Table 7 of GSTR-1 — not invoice-wise
• Buyer delivery address not mandatory if value < ₹50,000

B2CL — B2C Large Invoice

• Interstate B2C supplies of ₹2.5 lakh and above per invoice (₹1 lakh from August 1, 2024)
• Delivery address is mandatory
• State code of delivery location must be mentioned
• Reported invoice-wise in Table 5 of GSTR-1

Type 3 — Export Invoice

• Issued for export of goods or services to overseas buyers
• Must carry the declaration: "SUPPLY MEANT FOR EXPORT ON PAYMENT OF IGST" or "SUPPLY MEANT FOR EXPORT UNDER BOND/LUT WITHOUT PAYMENT OF IGST"
• Additional details required: Shipping Bill No., Shipping Bill Date, Port Code, Country of Destination
• Buyer name and destination country mentioned (no GSTIN needed)
• IGST is charged if export is with payment of tax (later refunded)
• Zero tax if export is under LUT/Bond

Type 4 — SEZ (Special Economic Zone) Invoice

• Supplies to SEZ developers or units are zero-rated supplies under IGST Act
• Invoice must state: "SUPPLY TO SEZ UNIT/SEZ DEVELOPER — WITH/WITHOUT PAYMENT OF IGST"
• GSTIN of SEZ unit must be mentioned with SEZ endorsement
• Reported in Table 6A of GSTR-1

Type 5 — RCM Invoice (Reverse Charge Mechanism)

• When the recipient is liable to pay GST instead of the supplier (Section 9(3)/9(4))
• Invoice must state: "TAX IS PAYABLE ON REVERSE CHARGE BASIS"
• Supplier issues a regular invoice without charging GST — recipient self-assesses and pays RCM tax
• Common RCM scenarios: GTA services, legal services by advocate to business, import of services, security services
• The recipient issues a self-invoice to record RCM liability

Type 6 — Bill of Supply (Composition Dealer / Exempt Supplies)

• Issued by Composition Scheme dealers — tax is not separately charged on invoice
• Must carry the statement: "Composition taxable person, not eligible to collect tax on supplies"
• Also issued for exempt or nil-rated supplies by regular taxpayers
• No GST line items on the bill of supply
• Buyer cannot claim ITC on Bill of Supply

6. E-Invoicing under GST — IRN, IRP, QR Code, Applicability & Exemptions

E-invoicing (Electronic Invoicing) is a mandatory system introduced under GST where B2B invoices must be authenticated in real-time by the Invoice Registration Portal (IRP) operated by the NIC. Upon submission, the IRP generates a unique Invoice Reference Number (IRN) — a 64-character hash — and a digitally signed QR code containing key invoice details.

E-invoicing does NOT mean generating invoices on a government portal. Businesses generate invoices in their own ERP/accounting software and then report JSON data to the IRP for authentication. The IRN and QR code returned by IRP must be printed on the invoice.

E-Invoice Applicability — Turnover Threshold

What E-Invoicing Covers

• B2B tax invoices, credit notes, and debit notes
• Supplies to SEZ units and developers
• Export invoices (outward supplies)
• B2C invoices are NOT covered (currently)

Who is Exempt from E-Invoicing (Even Above ₹5 Crore)?

• Banking companies, insurance companies, NBFCs
• Goods Transport Agency (GTA)
• Passenger transport services (bus, rail, flight)
• Multiplex cinema operators
• Special Economic Zone (SEZ) units (only units — not developers)
• Government departments and local authorities

30-Day IRN Reporting Rule (From April 1, 2025)

From April 1, 2025, businesses with AATO above ₹10 crore must report their B2B invoices to the IRP within 30 days from the invoice date. If an invoice dated 1st March 2026 is not reported by 31st March 2026, the IRP will reject the IRN generation request. This creates a serious ITC risk for buyers.

7. Time Limit for Issuing GST Invoice — Section 31

8. HSN Code & SAC Code on GST Invoice — Turnover-Based Requirement

HSN (Harmonized System of Nomenclature) codes are used to classify goods. SAC (Services Accounting Code) codes are used to classify services. Both are mandatory on all GST invoices as per Rule 46(a) of the CGST Rules.

Common SAC Codes for Services

9. GST Credit Note & Debit Note — Section 34, Format & Time Limits

Credit Note under Section 34(1)

A GST Credit Note is issued by the supplier when the taxable value or tax charged in the original invoice exceeds the actual amount — resulting in a reduction of the supplier's tax liability.

When to Issue a Credit Note:

• Goods returned by buyer (sales return)
• Services found deficient or not fully rendered
• Post-supply discount given to the buyer
• Original invoice value was incorrectly higher

Debit Note under Section 34(3)

A GST Debit Note is issued when the taxable value or tax charged in the original invoice is less than the actual amount — increasing the supplier's tax liability.

When to Issue a Debit Note:

• Additional goods supplied beyond original invoice
• Invoice raised for a lower amount than actual supply value
• Price revision upward after original invoicing

No time limit for Debit Note — it can be issued in any subsequent tax period.

Mandatory Fields on Credit Note / Debit Note

• Document type clearly stated: "Credit Note" or "Debit Note"
• Unique serial number (per financial year)
• Date of issue
• Original Tax Invoice number and date being revised
• Supplier GSTIN and recipient GSTIN
• Revised taxable value and tax amounts
• Reason for issuing the note

10. GST Invoice Cancellation & Amendment

Invoice Cancellation

There is no formal concept of "invoice cancellation" under CGST Act. However, a supplier can issue a credit note for the full value of the original invoice, effectively reversing it. For e-invoices, IRN can be cancelled within 24 hours of generation on the IRP portal — after 24 hours, the IRN cannot be cancelled, and a credit note must be issued instead.

Invoice Amendment in GSTR-1

An incorrect invoice reported in GSTR-1 can be amended in the subsequent tax period using Tables 9A, 9B, and 9C of GSTR-1:

• Table 9A: Amended B2B invoices
• Table 9B: Amended B2CL invoices
• Table 9C: Amended credit / debit notes

Amendment can be done up to 30th November of the following financial year or filing of Annual Return — whichever is earlier. Amendments affect GSTR-2B of the recipient in the amendment period.

11. GST Invoice Format for Services — Freelancers, Consultants & Professionals

For service providers — including freelancers, IT professionals, management consultants, CA/CS firms, architects, designers, marketing agencies — the GST invoice format differs slightly from goods invoices:

• SAC Code instead of HSN code for each service line item
• No Quantity / Unit column required (unlike goods) — though it can be mentioned (e.g., "1 Project", "20 Hours")
• Invoice must be issued within 30 days of rendering service (45 days for banking)
• If payment is received in advance (before service), a Receipt Voucher must be issued (not a tax invoice) at the time of receipt
• Tax Invoice must be issued once the service is rendered
• For ongoing/continuous services, invoice must be issued at each billing cycle

GST Rate for Common Professional Services

12. GST Invoice Reporting in GSTR-1 — Which Invoice Goes Where?

All outward supply invoices are reported in GSTR-1 (or GSTR-1A for amendments). Different invoice types are reported in different tables:

13. Penalties for GST Invoice Non-Compliance — Section 122 & 125

14. 15 Most Common GST Invoice Mistakes — And How to Avoid Them

• 1. Wrong GSTIN of Supplier or Buyer: Always cross-verify GSTIN from gst.gov.in. A single digit error makes the ITC invalid.
• 2. Duplicate Invoice Numbers: Invoice numbers must be unique within a financial year and series. Duplicates cause GSTR-1 upload rejection.
• 3. Missing or Incorrect HSN/SAC Code: Wrong HSN leads to wrong tax classification, ITC disputes, and audit issues.
• 4. Wrong Place of Supply: This is the most critical error — if place of supply is wrong, the entire tax type (IGST vs CGST+SGST) may be wrong, leading to demands with interest.
• 5. IGST charged on Intrastate supply (or vice versa): CGST+SGST must be charged for same-state transactions. Charging IGST instead is a serious compliance error.
• 6. Missing "Reverse Charge" Mention: For RCM supplies, omitting the mandatory RCM declaration on the invoice is a penalty-attracting error.
• 7. Invoice Not Issued Within Time Limit: Late invoicing shifts the time of supply, causing incorrect return period reporting and potential interest.
• 8. Taxable Value Not Correctly Computed: Taxable value = transaction value under Section 15. Discounts, subsidies, and inclusions/exclusions must be correctly applied.
• 9. Missing Ship-To Details for Different Delivery Location: When goods are delivered to a different address than the billing address, the delivery address must be explicitly stated.
• 10. No Authorized Signatory: An unsigned invoice is not a valid tax invoice — always ensure physical or digital signature.
• 11. Mismatch Between Invoice Amount and GSTR-1: If invoice data reported in GSTR-1 differs from the actual invoice, buyer's GSTR-2B will reflect wrong amount, leading to ITC mismatch notices.
• 12. Credit Note Issued After Time Limit: Late credit notes cannot be declared in GSTR-1 and ITC reversal by buyer cannot be tracked.
• 13. Not Generating IRN for E-Invoice Eligible Transactions: B2B invoices without IRN for ₹5 Cr+ taxpayers are treated as invalid and buyer loses ITC.
• 14. Incorrect Rate of Tax: Applying 12% when the correct rate is 18%, or treating a 5% item as 12% — creates both tax short-payment and ITC mismatch.
• 15. Not Mentioning "Interstate" or State Code on Invoice: Particularly important for B2CL, export, and SEZ invoices where state of delivery is a legal requirement.

15. How to Use the Excel GST Invoice Template

16. Frequently Asked Questions — GST Invoice Format