Mandatory Invoice Fields under Rule 46
Rule 46 of the CGST Rules prescribes the particulars a tax invoice must contain: a consecutive serial number (unique for the financial year, up to 16 characters), name/address/GSTIN of the supplier, invoice date, name/address/GSTIN of the recipient (mandatory if registered; for unregistered recipients where value exceeds ₹50,000, name and address are mandatory), HSN/SAC code, description and quantity of goods or services, taxable value, applicable GST rate, amount of tax (CGST/SGST/IGST/cess shown separately), place of supply for inter-state transactions, and signature of the supplier or authorized representative.
A missing or defective field is not a mere formality — an invoice that fails Rule 46 can be treated as invalid documentation for the recipient's ITC claim under Section 16, and can attract penalty under Section 122 for issuing an incorrect or incomplete invoice.
For taxpayers with aggregate turnover above the e-invoicing threshold (₹5 crore in any financial year from FY 2017-18 onwards, per the latest CBIC notification), every B2B invoice must additionally be reported to an Invoice Registration Portal (IRP) to obtain an Invoice Reference Number (IRN) and a signed QR code before the invoice is considered valid. An invoice above the threshold that is issued without a valid IRN is deemed not to have been issued at all under Rule 48(5), and the recipient is denied ITC on it.
This checker validates field completeness, HSN/SAC format, GSTIN checksum, and (where relevant) whether the invoice value and turnover profile mandate e-invoicing compliance, flagging gaps before they surface as GSTR-1 mismatches or ITC denial for your customers.
Worked Example: Common Invoice Defects Caught
A batch of 200 sales invoices is run through the checker for a business with ₹8 crore turnover (above the e-invoicing threshold).
Frequently Asked Questions (FAQs)
What happens if my e-invoice-eligible invoice does not have an IRN?
Under Rule 48(5), any invoice issued by a taxpayer above the e-invoicing threshold without a valid IRN is treated as if it was not issued at all. The recipient cannot claim ITC on it, and the supplier is exposed to penalty under Section 122 for non-compliant invoicing.
What is the current e-invoicing turnover threshold?
As per the latest CBIC notification, e-invoicing is mandatory for all registered persons whose aggregate turnover in any financial year from 2017-18 onwards exceeds ₹5 crore, for B2B supplies, B2B exports, and supplies to SEZ units.
Is HSN code mandatory on every invoice regardless of turnover?
Yes, but the number of digits required varies by turnover: 4-digit HSN for turnover up to ₹5 crore, and 6-digit HSN for turnover above ₹5 crore, per Notification No. 78/2020-Central Tax.
Can an invoice without the recipient's GSTIN still be valid?
Only for unregistered (B2C) recipients. For any B2B supply, the recipient's GSTIN is mandatory under Rule 46(f). For B2C supplies where the invoice value exceeds ₹50,000, the recipient's name and address must still be recorded even without a GSTIN.
Does a QR code replace the IRN requirement?
No, they serve different purposes but are both mandatory together for e-invoicing-eligible supplies: the IRN is the unique hash-based reference number generated by the IRP, and the QR code (embedding the IRN, invoice value, and key details) must be printed on the invoice for verification. Both are needed for the invoice to be legally valid under Rule 48.