Mandatory particulars
A tax invoice must carry all of the following. Most disputes come down to one of the last three.
- Supplier's name, address and GSTIN
- A consecutive serial number, unique for the financial year
- Date of issue
- Recipient's name, address and GSTIN where registered
- HSN or SAC code for each line
- Description, quantity, unit and taxable value per line
- Rate and amount of CGST, SGST/UTGST or IGST, shown separately
- Place of supply, and the state code for inter-state supplies
- Whether tax is payable on reverse charge
- Signature or digital signature of the supplier
Tax invoice vs bill of supply
A tax invoice is issued when you charge GST. A bill of supply is issued when you cannot — for exempt supplies, or if you are registered under the composition scheme. A composition dealer's bill of supply must also state that they cannot collect tax on supplies.
Credit and debit notes
If the taxable value or tax on an invoice needs to come down — a return, a discount agreed after the fact, an overcharge — you issue a credit note. If it needs to go up, a debit note. Both must reference the original invoice, and credit notes have a deadline: they must be declared by 30 November following the financial year, or the corresponding tax adjustment is lost.
Invoice numbering
Series must be consecutive and unique within a financial year, and may not exceed sixteen characters. You can run separate series for different branches or document types, but gaps and duplicates draw scrutiny during reconciliation because the department matches your series against what your customers claim.
Common questions
Can I issue an invoice without the customer's GSTIN?+
Yes, for B2C sales — the GSTIN field only applies where the recipient is registered. But without it the sale is reported as B2C in GSTR-1 and your customer cannot claim input credit, so registered buyers will always ask for it to be captured.
How many copies of an invoice do I need?+
For goods, three: original for the recipient, duplicate for the transporter, triplicate for the supplier. For services, two: original for the recipient and duplicate for the supplier.
Do I need to print HSN codes on every invoice?+
Yes, though the required precision depends on turnover — smaller businesses report at four digits and larger ones at six. Since the code also drives the tax rate, it is worth storing on the item rather than typing per invoice.