Invoice numbering rules under GST

GST law is specific about invoice numbers, and getting this right avoids notices.

The rules

• The number must be consecutive and unique within a financial year
• It can be up to 16 characters, using letters, digits, slash and hyphen
• You may run separate series (for example a prefix per branch), as long as each is consecutive

Practical tip

Pick a simple prefix like INV and let numbering run automatically. Lekhae assigns a clean consecutive number and blocks duplicates for you.