Since the Goods and Services Tax (GST) was introduced in India in July 2017, every registered business must issue GST-compliant invoices for taxable supplies. Getting the format wrong can mean your customer cannot claim Input Tax Credit (ITC), leading to disputes and financial losses. This guide covers every mandatory field, how to split CGST, SGST, and IGST correctly, when HSN codes are required, and what e-invoicing means for your business in 2026.
A GST invoice is a document issued by a registered supplier to a recipient when a taxable supply of goods or services occurs. It serves as the primary document for the recipient to claim Input Tax Credit under GST law. A "tax invoice" (as opposed to a bill of supply) must be issued by a regular taxpayer when the supply is taxable.
| Document | When to use |
|---|---|
| Tax Invoice | Regular taxable supply by a GST-registered business |
| Bill of Supply | Exempt supplies, or when you are a composition scheme dealer |
| Aggregate Invoice | Multiple invoices to unregistered recipients in one day, each below ₹200 |
| Debit/Credit Note | Adjustments to a previously issued tax invoice |
Rule 46 of the CGST Rules 2017 specifies the mandatory details that must appear on every tax invoice:
| Field | Details |
|---|---|
| Supplier's name, address, and GSTIN | Your registered business details |
| Invoice serial number | Consecutive, unique per financial year (e.g., INV/2026-27/001) |
| Date of issue | Date the invoice is issued |
| Recipient's name, address, and GSTIN | Required for B2B; for B2C above ₹50,000, name and address of recipient |
| HSN/SAC code | Harmonized System Nomenclature for goods; Service Accounting Code for services |
| Description of goods or services | Clear description of what is being supplied |
| Quantity and unit | For goods: number of items and unit of measurement |
| Total value (taxable value) | Value before GST |
| Rate and amount of CGST, SGST/UTGST, or IGST | Split correctly based on supply type |
| Place of supply (state) | Required for interstate supplies |
| Whether supply is on reverse charge basis | Yes/No declaration |
| Signature or digital signature | Of supplier or authorised representative |
The correct tax split depends on whether the supply is intra-state or inter-state.
| Supply Type | Tax Applied | Example |
|---|---|---|
| Intra-state (within same state) | CGST + SGST (equal split) | Supplier in Mumbai → Customer in Mumbai: 9% CGST + 9% SGST = 18% GST |
| Inter-state (between states) | IGST (full rate) | Supplier in Mumbai → Customer in Delhi: 18% IGST |
| Union Territory supply | CGST + UTGST | Supplier in Delhi → Customer in Chandigarh: CGST + UTGST |
Practical tip: The "place of supply" determines which state the GST revenue goes to — not where the supplier is located. For services, the place of supply is typically the location of the recipient.
| GST Rate | Category |
|---|---|
| 0% | Essential goods: most food items, books, newspapers, sanitary napkins |
| 5% | Apparel below ₹1,000, footwear below ₹1,000, certain food products |
| 12% | Processed foods, computers, mobile phones (selected), hotel rooms ₹1,001–₹7,500 |
| 18% | Most services, electronics, capital goods, IT services, telecom |
| 28% | Luxury goods, automobiles, cement, air conditioners, tobacco |
The HSN (Harmonized System of Nomenclature) code identifies the category of goods. SAC (Service Accounting Code) does the same for services. The number of digits required depends on your annual turnover:
| Annual Turnover | HSN Digits Required |
|---|---|
| Up to ₹5 crore | 4 digits |
| Above ₹5 crore | 6 digits |
For composition scheme dealers, HSN codes are not required. For exports, 8-digit HSN codes are mandatory.
E-invoicing is mandatory for businesses with an annual aggregate turnover above ₹5 crore (as of August 2023). Under the e-invoicing system:
Important: Businesses below the ₹5 crore threshold are not required to use e-invoicing, but should ensure their invoice format is still GST-compliant with all mandatory fields.
GST invoices must be numbered consecutively and uniquely per financial year. The GSTN recommends a format that includes the financial year (e.g., INV/2026-27/001). Key rules:
| Supply Type | Time Limit |
|---|---|
| Goods (not continuous supply) | At or before delivery / removal of goods |
| Goods (continuous supply) | On or before the due date of payment |
| Services (not continuous) | Within 30 days of service completion (45 days for banking/insurance) |
| Services (continuous supply) | On or before the due date of payment per contract |
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Create GST Invoice FreeYes, for every taxable supply by a registered person. For B2C sales below ₹200 to unregistered recipients, you may issue a consolidated invoice at the end of the day instead of individual invoices.
No. Composition scheme dealers cannot charge GST or issue a tax invoice. They must issue a "Bill of Supply" instead and cannot collect GST from customers.
Your customer will not be able to claim Input Tax Credit, which may lead to disputes. You should issue a revised/corrected invoice or a credit note followed by a fresh invoice.
Yes. Exports are zero-rated under GST. The invoice must clearly state "Supply Meant for Export Under Bond/LUT Without Payment of IGST" or "Supply Meant for Export on Payment of IGST." The shipping bill serves as the export declaration.