📌 Key Takeaway: Master the statutory requirements of Rule 46 of the CGST Rules. Learn the 16 mandatory invoice fields, consecutive numbering rules, B2B vs B2C compliance, and e-invoicing limits.
The Legal Importance of a Compliant GST Tax Invoice
Under Section 31 of the CGST Act read with Rule 46 of the CGST Rules, 2017, a tax invoice is the primary statutory document establishing that taxable supply has occurred. For your B2B corporate buyers, a legally compliant invoice is the absolute prerequisite for claiming Input Tax Credit (ITC) under Section 16(2). An invoice with missing mandatory fields can lead to immediate ITC rejection and audit scrutiny.
16 Mandatory Particulars Required on Every GST Tax Invoice
Every valid GST tax invoice issued by a registered taxpayer must contain the following 16 specific data points:
- Supplier's Legal Name, Registered Trade Name, Full Address, and 15-digit GSTIN.
- Consecutive Serial Number (unique for the financial year, up to 16 alphanumeric characters).
- Date of Invoice Issuance.
- Recipient's Name, Address, and GSTIN/UIN (for B2B registered customers).
- Place of Supply along with State Name and 2-digit State Code (critical for CGST/SGST vs IGST determination).
- Delivery Address where different from recipient billing address.
- Harmonized System of Nomenclature (HSN) Code for goods or Service Accounting Code (SAC) for services.
- Comprehensive Description of goods or services provided.
- Quantity and Unit of Measure (UOM).
- Total Value of Goods or Services.
- Taxable Value of Supply after deducting trade discounts.
- Applicable Rate of GST (e.g., 5%, 12%, 18%, or 28%).
- Segregated Amount of Tax charged: Central GST (CGST), State GST (SGST), and Integrated GST (IGST).
- Reverse Charge declaration (whether tax is payable on RCM basis).
- Signature or Digital Signature Certificate (DSC) of supplier or authorized representative.
- Quick Response (QR) Code for B2C dynamic UPI invoices or IRN QR code for e-invoicing entities.
HSN Code Reporting Mandate
Businesses with annual turnover up to ₹5 Crores must report at least a 4-digit HSN code for B2B supplies. Businesses with aggregate turnover exceeding ₹5 Crores must compulsorily report a 6-digit HSN/SAC code on all B2B and export invoices.
E-Invoicing Applicability (₹5 Crore Threshold)
Taxpayers whose aggregate annual turnover exceeded ₹5 Crores in any preceding financial year from 2017-18 onwards must generate electronic invoices via the Invoice Registration Portal (IRP). Every B2B invoice must bear a 64-character Invoice Reference Number (IRN) and a digitally signed cryptographic QR code.