What are the mandatory fields in a GST invoice in India?

Under Rule 46 of the CGST Rules, a GST invoice must contain: 1) Supplier name, address & GSTIN, 2) Consecutive invoice number (max 16 chars), 3) Invoice date, 4) Recipient name, address & GSTIN (for B2B), 5) HSN/SAC code, 6) Description of goods/services, 7) Quantity and unit, 8) Total value and taxable value, 9) GST rate and tax amounts (CGST, SGST, IGST), 10) Place of supply and state name, 11) Reverse charge indicator, and 12) Signature or digital signature.

What are the GST invoice numbering rules?

A GST invoice serial number must be consecutive, unique for each financial year, contain only alphanumeric characters and special characters hyphen (-) and slash (/), and must not exceed 16 characters in length (e.g., INV/2025-26/001).

What is the time limit for issuing a GST tax invoice?

For supply of goods: On or before the time of removal of goods for delivery to the recipient. For supply of services: Within 30 days from the date of the supply of service (or within 45 days for banking, insurance, and financial institutions).

How many digits of HSN code are required on a GST bill?

Businesses with annual aggregate turnover up to ₹5 Crore must mention at least 4 digits of HSN code on B2B invoices (optional for B2C). Businesses with turnover above ₹5 Crore must mention 6 digits of HSN code for all B2B and B2C invoices. For chemical, import, and export trade, 8 digits are mandatory.

What is the difference between a Tax Invoice and a Bill of Supply?

A Tax Invoice is issued by regular registered GST taxpayers charging tax on taxable goods or services, enabling the buyer to claim Input Tax Credit (ITC). A Bill of Supply is issued by taxpayers under the Composition Scheme or by businesses dealing exclusively in exempt or nil-rated goods where no GST can be charged.

Is a physical signature mandatory on computer-generated GST invoices?

Under the CGST Rules, a physical signature is not mandatory if the tax invoice is issued digitally with an authorized digital signature or if it is generated electronically under the Information Technology Act provisions containing a system-generated statement.

GST Invoice Format 2026 — Mandatory Rules, Fields & Free Template

Under Section 31 of the Central Goods and Services Tax (CGST) Act, 2017 read with Rule 46 of the CGST Rules, every registered person supplying taxable goods or services must issue a Tax Invoice containing specific mandatory details. A defective invoice can disqualify your customer from claiming Input Tax Credit (ITC) and trigger financial penalties under GST Section 122.

1. Visual Sample GST Invoice Format

While the Government does not mandate an identical graphic layout, your invoice layout must clearly present all prescribed fields. Below is a standard, fully compliant GST invoice format:

XYZ ENTERPRISES PRIVATE LIMITED

102, Nariman Point, Mumbai, Maharashtra - 400021
GSTIN: 27AABCU9603R1ZM • State: Maharashtra (Code: 27)
Email: contact@xyzent.com • Phone: +91 98765 43210

TAX INVOICE

Bill To (Recipient Details)

ABC TRADING CORP
45, Industrial Area, Whitefield, Bengaluru, Karnataka - 560066
GSTIN: 29AAACA1234F1Z5 • State: Karnataka (Code: 29)
Place of Supply (POS): 29 - Karnataka (Inter-State)

Invoice Information

Invoice Number: INV/2025-26/0482
Invoice Date: 15-Oct-2025
Due Date: 30-Oct-2025
Reverse Charge (RCM): No • e-Way Bill No: 241089201948

#	Item Description	HSN/SAC	Qty	Unit	Rate (₹)	Taxable Value	IGST (18%)	Amount (₹)
1	High-Performance Industrial Air Filter	8421	10	NOS	2,000.00	20,000.00	3,600.00	23,600.00
2	Installation & Setup Services	9987	1	JOB	5,000.00	5,000.00	900.00	5,900.00

Amount in Words: Twenty-Nine Thousand Five Hundred Rupees Only

Bank Details: HDFC Bank • A/C: 50200012345678 • IFSC: HDFC0000123

Subtotal: ₹25,000.00

IGST (18%): ₹4,500.00

Total: ₹29,500.00

2. The 16 Mandatory Fields in a GST Invoice (Rule 46)

According to Rule 46 of the CGST Rules, a tax invoice issued by a registered person must strictly contain the following 16 particulars:

Supplier Details

Name, registered address, and 15-digit GSTIN of the supplier.

Serial Number

Consecutive serial number not exceeding 16 characters, unique for the financial year.

Invoice Date

Date of issuing the tax invoice.

Recipient GSTIN / UIN

Name, address, and GSTIN/Unique Identification Number of registered buyer.

Unregistered Recipient Details

For B2C sales ≥ ₹50,000: Name, delivery address, state name, and state code.

HSN / SAC Code

Harmonized System of Nomenclature code for goods or Accounting Code for services.

Item Description

Clear description of goods supplied or professional services rendered.

Quantity and Unit

Quantity in units of measure (e.g. PCS, KGS, MTR, BOX, NOS, HRS).

Total Value

Gross amount of goods or services prior to trade discounts.

Taxable Value

Net value after deducting trade discounts or volume abatements.

Tax Rates

Applicable GST rate (0%, 5%, 12%, 18%, 28%) and cess if applicable.

Tax Amounts

Individual amounts charged as CGST, SGST, IGST, or UTGST.

Place of Supply (POS)

State name and 2-digit state code where delivery is deemed to occur.

Delivery Address

Mandatory if delivery address differs from place of supply (Bill-To vs Ship-To).

Reverse Charge Indication

Clear declaration whether tax is payable under Reverse Charge (RCM: Yes/No).

Authorized Signature

Signature or digital signature of supplier or authorized representative.

3. Strict GST Invoice Serial Numbering Rules

Many businesses make mistakes when numbering their invoices. The GST Council mandates strict formatting constraints for invoice series under Rule 46(b):

Maximum 16 Characters: The invoice serial number cannot exceed 16 alphanumeric characters.
Allowed Characters: Only letters (A–Z), numbers (0–9), and special characters hyphen (-) and slash (/) are allowed. Spaces, underscores (_), and symbols like # or @ are prohibited.
Consecutive & Unique: Numbering must be strictly consecutive and unique for every financial year (1st April to 31st March).
Best Practice Pattern: Recommended format examples include:
- INV/25-26/001
- DEL-2025-001
- AB/2526/0089

4. HSN / SAC Code Digits Required on Invoices

Notification No. 78/2020 – Central Tax defines the minimum HSN (Harmonised System of Nomenclature) digits that must appear on your invoices based on your business turnover:

Aggregate Turnover up to ₹5 Crore: Minimum 4 digits of HSN code on B2B invoices. (Optional on B2C invoices).
Aggregate Turnover above ₹5 Crore: Minimum 6 digits of HSN code on all B2B and B2C invoices.
Import and Export Invoices: Mandatory 8 digits of HSN code regardless of turnover.

Need to look up the correct HSN code for your items? Use our Free HSN Code Finder to search over 10,000+ goods and service codes.

5. Time Limits for Issuing a GST Invoice

Under Section 31 of the CGST Act, you must issue tax invoices within specific statutory deadlines:

Supply of Goods (Normal Supply): On or before the time of removal of goods for delivery to the recipient.
Supply of Goods (Continuous Supply): On or before the issuance of account statements or receipt of payment.
Supply of Services: Within 30 days from the date of completion of service.
Banking and Insurance Companies: Within 45 days from the date of supply of service.

6. Tax Invoice vs. Bill of Supply vs. Proforma Invoice

Not every bill created under GST is a Tax Invoice. Here is how different documents compare:

Document Type	Issued By	Can Tax Be Charged?	Can Buyer Claim ITC?
Tax Invoice	Regular registered GST dealer	Yes (CGST/SGST/IGST)	Yes
Bill of Supply	Composition dealer or exempt goods seller	No (0% tax)	No
Proforma Invoice	Seller (quotation / pre-shipment)	Estimated only (preliminary)	No (Non-tax document)
Delivery Challan	Consignor (job work, goods on approval)	No tax levied	No

7. Frequently Asked Questions

Can I issue a handwritten GST invoice in 2026? +

Yes, manual paper-based handwritten invoices are legally permissible under GST as long as they contain all 16 mandatory fields prescribed under Rule 46. However, computer-generated invoices are strongly recommended to avoid computational errors, GSTR-1 mismatches, and illegible tax entries.

What happens if an invoice does not have an HSN code? +

Missing or incorrect HSN codes violate Rule 46 and can result in general penalties under Section 125 of the CGST Act (up to ₹25,000). More importantly, the GST portal e-way bill generation and GSTR-1 filing will block or flag invoices missing mandatory HSN digits.

What is the e-invoicing threshold in India in 2026? +

Electronic Invoicing (e-invoicing) is mandatory for all registered businesses whose aggregate annual turnover exceeded ₹5 Crore in any preceding financial year from 2017–18 onwards. Eligible businesses must upload invoices to the Invoice Registration Portal (IRP) to generate an IRN and QR Code.

How many copies of a GST invoice must be prepared? +

For supply of goods: 3 copies — Original for Recipient, Duplicate for Transporter, and Triplicate for Supplier. For supply of services: 2 copies — Original for Recipient and Duplicate for Supplier.

Is it mandatory to mention Bank Details on a GST Invoice? +

While bank account details are not strictly mandatory under Rule 46, mentioning your Bank Name, Account Number, and IFSC Code is standard business practice across India to expedite NEFT/RTGS payments from B2B clients.

Official GST Invoice Format India 2026: Rules & Free Template