GST Invoice explained: this guide covers what GST Invoice means, who it applies to, the step-by-step process, documents required, fees, due dates and penalties in India — so you can stay compliant with confidence and avoid costly mistakes.
What is a GST Invoice?
A GST invoice (also called a Tax Invoice under GST) is a commercial document issued by a registered supplier for the supply of taxable goods or services. It serves as proof of sale, enables the buyer to claim Input Tax Credit (ITC), and is a key compliance document under the GST framework.
Issuing a proper GST invoice is mandatory for all registered taxpayers making taxable supplies. An invoice with missing mandatory fields can result in the buyer losing their ITC, and the supplier facing penalties.
- Mandatory for: All registered suppliers of taxable goods/services
- Not required for: Exempt supplies (issue Bill of Supply instead)
- Time limit: Goods — before/at delivery; Services — 30 days from supply date
- E-invoicing (IRP): Mandatory for businesses with turnover > ₹5 crore
- Invoice serial number must be unique within a financial year
Mandatory Fields in a GST Tax Invoice
Under Rule 46 of CGST Rules, every GST tax invoice must contain the following information:
| # | Mandatory Field | Notes |
|---|---|---|
| 1 | Name, address, and GSTIN of supplier | Must match registration records |
| 2 | Nature of document (Tax Invoice) | Must be printed at top |
| 3 | Consecutive serial number (unique per FY) | Can contain letters, numbers, /, -, _ characters. Max 16 characters. |
| 4 | Date of issue | |
| 5 | Name, address, and GSTIN of recipient (B2B) | For B2C > ₹2.5L: name and address; no GSTIN needed |
| 6 | HSN code of goods or SAC code of services | 2/4/6/8 digits depending on annual turnover |
| 7 | Description of goods or services | |
| 8 | Quantity and unit of measurement (for goods) | |
| 9 | Taxable value (after discounts) | |
| 10 | Rate of tax (CGST, SGST/UTGST, or IGST) | Show each rate separately |
| 11 | Tax amount (CGST, SGST/UTGST, or IGST) | Show each amount separately |
| 12 | Place of supply (state name and code) | Critical for determining IGST vs CGST+SGST |
| 13 | Address of delivery (if different from recipient address) | |
| 14 | Whether tax is payable on reverse charge basis | Write "Yes" or "No" |
| 15 | Signature or digital signature of supplier | Physical or digital |
CGST vs SGST vs IGST: When to Apply Which?
| Type of Supply | Tax Applied | Who Gets the Revenue |
|---|---|---|
| Intra-state supply (supplier and customer in same state) | CGST + SGST (each at half the total rate) | Centre (CGST) + State (SGST) |
| Inter-state supply (supplier and customer in different states) | IGST (at full rate) | Centre (shared with state later) |
| Import of goods/services | IGST + Customs duty | Centre |
| Export of goods/services | Zero-rated (0% GST or refund of ITC) | — |
Example: A supplier in Maharashtra sells to a buyer in Maharashtra. GST rate is 18% — so apply CGST 9% + SGST 9% (Maharashtra). If the buyer is in Delhi — apply IGST 18%.
HSN Code Requirements in GST Invoice
| Annual Aggregate Turnover | HSN Digits Required |
|---|---|
| Up to ₹5 crore | 4-digit HSN code |
| Above ₹5 crore | 6-digit HSN code |
| Export invoices | 8-digit HSN code (mandatory) |
Service providers use SAC (Services Accounting Code) — 6-digit codes for all service categories.
GST Invoice Format: Sample
TAX INVOICE
Supplier Details: Invoice No.: INV-2025-001
Invoice Date: 15/06/2025
Place of Supply: Maharashtra (27)
GSTIN: 27XXXXX0000X1ZX
Bill To: Ship To (if different):
GSTIN: 27YYYYY0000Y1ZY
+---------+------------+------+------+------------+------+------+------+--------+
| HSN/SAC | Description| Qty | Unit | Taxable Val| CGST | SGST | IGST | Total |
+---------+------------+------+------+------------+------+------+------+--------+
| 8471 | Laptop | 2 | Nos | ₹80,000 | 9% | 9% | — |₹94,400 |
| | | | | |₹7,200|₹7,200| | |
+---------+------------+------+------+------------+------+------+------+--------+
| Total | | | | ₹80,000 |₹7,200|₹7,200| — |₹94,400 |
+---------+------------+------+------+------------+------+------+------+--------+
Tax Amount in Words: Rupees Ninety Four Thousand Four Hundred Only
Whether tax payable on reverse charge: No
Authorised Signatory: _______________
GST Invoice vs Bill of Supply
| Feature | Tax Invoice | Bill of Supply |
|---|---|---|
| When issued | For taxable supplies | For exempt supplies or by composition dealers |
| Shows GST | Yes — CGST, SGST, or IGST shown separately | No — no GST charged |
| Buyer can claim ITC | Yes | No |
| Who issues | Regular GST taxpayers | Composition dealers + regular dealers for exempt goods |
Time Limit to Issue GST Invoice
| Type of Supply | Time Limit |
|---|---|
| Supply of goods (normal) | On or before delivery of goods |
| Supply of goods (continuous supply) | Before / at the time each statement of accounts is issued |
| Supply of services (normal) | Within 30 days of date of supply of service |
| Supply of services (banking / insurance / telecom) | Within 45 days |
| Reverse charge supply | Same day as date of supply |
E-Invoicing Under GST
E-invoicing is mandatory for businesses with aggregate annual turnover exceeding ₹5 crore. Under e-invoicing:
- Invoices must be registered with the Invoice Registration Portal (IRP) — gst.gov.in IRP or GSTN-notified IRP
- IRP validates the invoice and generates a unique Invoice Reference Number (IRN) and QR code
- IRN and QR code must be printed on the physical invoice
- GSTR-1 is auto-populated from e-invoices — reduces manual data entry
- Buyers can verify invoice authenticity by scanning the QR code
Turnover threshold timeline:
- ₹500 crore+ turnover: Mandatory since 1 October 2020
- ₹100 crore+ turnover: Mandatory since 1 January 2021
- ₹50 crore+ turnover: Mandatory since 1 April 2021
- ₹20 crore+ turnover: Mandatory since 1 April 2022
- ₹10 crore+ turnover: Mandatory since 1 October 2022
- ₹5 crore+ turnover: Mandatory since 1 August 2023
Credit Note and Debit Note Under GST
When an invoice needs to be revised:
- Credit Note: Issued when taxable value or tax charged in the invoice is higher than what should have been charged (e.g., goods returned, discount given, price reduction). Reduces supplier's output tax and buyer's ITC.
- Debit Note: Issued when taxable value or tax charged is lower than what should have been (e.g., additional charges, price increase). Increases supplier's output tax.
- Credit/debit notes must be reported in GSTR-1 and GSTR-3B.
- Time limit: By September 30 of the next financial year or filing of annual return, whichever is earlier.
Common GST Invoice Mistakes
- Missing GSTIN of buyer: For B2B supplies, buyer's GSTIN is mandatory — without it, buyer cannot claim ITC
- Wrong place of supply: Determines CGST+SGST vs IGST — wrong classification means wrong tax collected
- Incorrect HSN/SAC code: Attracts wrong tax rate and penalties
- Not mentioning reverse charge: "Whether RCM applicable" must always appear
- Non-sequential numbering: Invoice numbers must be unique and sequential within a FY
- Issuing invoice after time limit: Late invoices attract penalty under Section 122
- Duplicate invoice numbers: Causes GSTR-1 filing errors and audit issues
Penalty for Not Issuing or Incorrect GST Invoice
- Penalty for non-issuance of invoice: ₹10,000 per invoice or the amount of tax involved, whichever is higher
- Incorrect invoice (wrong GSTIN, wrong tax rate): ₹10,000 or tax amount, whichever is higher
- E-invoicing non-compliance: Invoice treated as invalid; buyer cannot claim ITC on such invoices
Key Facts About GST Invoice
- Applies in: All states across India, under the relevant central law.
- Mode: Mostly online via the official government portal.
- Typical timeline: Ranges from a few days to a few weeks depending on the case.
- Non-compliance: May attract penalties, interest or late fees.
- Expert help: TaxClue completes GST Invoice end to end for you.
What is GST Invoice?
GST Invoice is an important compliance and legal topic for businesses and individuals in India. This guide explains its meaning, applicability and key requirements in simple language so you can understand and stay fully compliant.
Who needs to know about GST Invoice?
Business owners, startups, professionals, and taxpayers dealing with GST Invoice should understand the applicable rules. Requirements can vary by turnover, entity type and activity, so it is best to confirm your specific case before proceeding.
Over 90% of compliance penalties in India arise from missed due dates — timely handling of GST Invoice can save businesses thousands of rupees each year.
GST Invoice: a key compliance topic in Indian tax and corporate law that businesses and individuals must understand to remain compliant.