GST Invoice Rules — What You Need to Know

Under Section 31 of the CGST Act and Rule 46 of CGST Rules, every registered person supplying goods or services must issue a tax invoice. The invoice must be issued before or at the time of supply.

Mandatory Fields in a GST Invoice (Rule 46)

1. Supplier's name, address, and GSTIN
2. A consecutive serial number (max 16 characters, unique per financial year)
3. Date of issue
4. Recipient's name, address, and GSTIN (for B2B)
5. HSN code (4 digits up to ₹5 Cr turnover, 6 digits above)
6. Description of goods or services
7. Quantity and unit (for goods)
8. Taxable value (after discount)
9. Tax rate (CGST, SGST/UTGST, IGST) and tax amount
10. Place of supply (with state code)
11. Total invoice value
12. Signature or digital signature

Invoice Numbering Rules

Invoice numbers must be sequential, not exceeding 16 characters, and contain only alphabets, numerals, special characters (dash, slash). A new series can be started each financial year. Example: INV/2026-27/001.

E-Invoicing Requirements

From August 2023, e-invoicing is mandatory for businesses with aggregate turnover exceeding ₹5 crore. This means generating an Invoice Reference Number (IRN) from the Invoice Registration Portal (IRP) within 30 days of invoice date.

This tool generates the invoice content — for e-invoicing compliance, you'll also need to upload the invoice JSON to the IRP portal or use an integrated solution like 1010.

Frequently Asked Questions

What are the mandatory fields in a GST invoice?

Supplier GSTIN, sequential invoice number (max 16 chars), date, recipient GSTIN (B2B), HSN/SAC code, description, quantity, taxable value, tax rate and amount, place of supply, and total value.

What is the GST invoice format for 2026?

No mandatory prescribed format — any layout containing all Rule 46 mandatory fields is valid. This tool generates a clean format meeting all requirements.

Is HSN code mandatory on GST invoice?

Yes. 4-digit HSN for turnover up to ₹5 Cr, 6-digit for above ₹5 Cr. Mandatory on all B2B invoices and B2C invoices for businesses above ₹5 Cr turnover.

Can I use this invoice for GST filing?

Yes, it contains all fields required under Rule 46. Valid for GSTR-1 reporting and customer ITC claims. For e-invoicing (turnover >₹5 Cr), additionally obtain an IRN.