GST Invoice Rules 2026: Mandatory Particulars, Slabs & Penalties Explained

Issuing an invalid or non-compliant invoice under the Central Goods and Services Tax (CGST) Act can lead to severe penalties, vehicle interception during transport, and disqualification of your buyer's Input Tax Credit (ITC). In 2026, the GST Council and Central Board of Indirect Taxes and Customs (CBIC) have stepped up automated return matching, making invoice accuracy mandatory for every registered business in India.

The 16 Mandatory Particulars Under CGST Rule 46

According to Rule 46 of the CGST Rules, 2017, every tax invoice issued by a registered person must contain the following 16 specific details:

1. Name, Address, and GSTIN of the supplier.
2. Consecutive Serial Number: Not exceeding 16 characters, containing alphabets, numerals, or special characters (hyphen or slash), unique for each financial year.
3. Date of Issue: The formal calendar date the invoice was generated.
4. Name, Address, and GSTIN / UIN of the recipient (if registered).
5. Recipient Address of Delivery: Mandatory if recipient is unregistered and the taxable supply value is ₹50,000 or more, including State Name and State Code.
6. HSN Code of Goods or SAC Code of Services: Harmonized System of Nomenclature classification code.
7. Description of Goods or Services: Clear specification of the items supplied.
8. Quantity: Number of units, kilograms, metres, or standard unit quantity code (UQC).
9. Total Value of Supply: Gross product/service price before discounts.
10. Taxable Value: Total value taking into account any discount or abatement.
11. Applicable Tax Rate: Exact percentage slabs (0%, 5%, 12%, 18%, or 28%).
12. Tax Breakup: Segregated amounts showing Central Tax (CGST), State Tax (SGST), Integrated Tax (IGST), and Cess.
13. Place of Supply (POS): Name of the destination State along with State Code.
14. Address of Delivery: If different from the place of supply.
15. Reverse Charge Declaration: Stating whether tax is payable on reverse charge basis (Yes/No).
16. Signature or Digital Signature: Physical signature of supplier/authorized representative, or valid electronic signature (as per Rule 46 proviso).

HSN Code Requirements: 4 Digits vs 6 Digits

The CBIC requires businesses to declare HSN codes on tax invoices according to their Aggregate Annual Turnover (AATO):

• Turnover up to ₹5 Crores: Mandatory minimum of 4 digits of HSN code on B2B tax invoices (optional on B2C supplies).
• Turnover above ₹5 Crores: Mandatory minimum of 6 digits of HSN code on all B2B and B2C tax invoices.
• Chemical and pharma products: Certain designated bulk chemical supplies mandate full 8-digit HSN codes regardless of turnover.

E-Invoicing Rules in 2026

Under Rule 48(4) of the CGST Rules, registered entities whose aggregate annual turnover exceeded ₹5 Crores in any preceding financial year since 2017–18 are legally mandated to generate electronic invoices (e-invoicing). This involves submitting JSON payload data to an approved Invoice Registration Portal (IRP) such as NIC to obtain a 64-character Invoice Reference Number (IRN) and a digitally signed QR code.

Any tax invoice issued by an e-invoicing-mandated taxpayer without an approved IRN is legally treated as an invalid document. The buyer cannot claim ITC, and the seller faces penalties under Section 122.

Intra-State vs Inter-State Tax Calculations

Penalties for Invoicing Errors Under Section 122

Under Section 122 of the CGST Act, issuing an invoice without supplying goods/services, or issuing an incorrect invoice that leads to short payment of tax, attracts a penalty of ₹10,000 or 100% of the tax involved (whichever is higher). Routine clerical errors can lead to audit scrutiny and interest charges under Section 50 at 18% per annum.

How MsgBill Keeps You 100% GST Compliant

MsgBill's bill generator automates compliance so you never worry about math errors or missing fields:

• Automatic split between CGST+SGST vs IGST based on State selection.
• Exact two-decimal rounding without floating-point math errors.
• Automated sequential invoice numbering that adheres to financial year rules.
• Clean, printable PDF format containing all Rule 46 requirements.