Rule 46 of the CGST Rules sets out what a tax invoice has to contain. It applies to you if you are registered under GST and making a taxable supply. Below is the full list in plain language, with a note on the ones that actually go wrong.
The fields
| Field | Worth knowing |
|---|---|
| Your name, address and GSTIN | The registered name, not a trading name you use informally. |
| A serial number | Consecutive, unique within the financial year, at most 16 characters. Letters, digits, hyphen and slash only. |
| Date of issue | — |
| Customer's name, address and GSTIN or UIN | Required whenever they are registered. Their GSTIN is what lets them claim the credit, so a typo here is their problem to chase. |
| Unregistered customer details on higher-value invoices | Where the customer is unregistered and the invoice value is ₹50,000 or more, you must carry their name, address, the delivery address, and the state with its code. |
| HSN code, or SAC for services | Per line. The number of digits required depends on your turnover. |
| Description of the goods or services | — |
| Quantity and unit | For goods. A unit quantity code, e.g. NOS, KGS, MTR. |
| Total value of the supply | — |
| Taxable value | After any discount. This is the figure tax is charged on, and it is a separate column from the gross value. |
| Rate of each tax | CGST, SGST or UTGST, IGST and cess, shown separately. Never one merged "GST 18%" line on an intra-state invoice. |
| Amount of each tax charged | Again per head, not merged. |
| Place of supply, with the state name | Mandatory on inter-state supplies. This is the single most commonly missing field. |
| Address of delivery, if different from the place of supply | — |
| Whether tax is payable on reverse charge | Has to be stated on the face of the invoice when it applies. |
| Signature | Yours or an authorised representative’s, physical or digital. A digitally signed invoice does not need a handwritten one. |
The four that go missing most often
Place of supply on an inter-state invoice
Easy to skip, because the invoice looks complete without it and the total is right. It is mandatory whenever the supply is inter-state, and it is the field that justifies why you charged IGST rather than CGST and SGST. Which one applies is worth being sure about before you worry about printing it.
The tax heads shown separately
An intra-state invoice carries CGST and SGST as two lines, each with its own rate and amount. A single merged "GST 18% — ₹1,800" line does not satisfy the rule, even though the arithmetic is identical, because your customer files the two halves separately.
Taxable value as its own column
Where there is a discount, the gross value and the taxable value are different numbers and both belong on the invoice. Showing only the final figure hides the base the tax was actually computed on.
A serial number that survives the year
The number must be consecutive, unique within the financial year, and no longer than 16 characters. A format like INV/2026-27/0001 is 16 exactly. Add a longer prefix and you are over the limit — which is why a branch code bolted onto the front is a common way to end up with technically invalid invoices. See the numbering section for what happens on 1 April.
What is convention rather than requirement
Two things appear on almost every Indian invoice and are worth including, but are not in Rule 46:
- The total in words. Long-standing commercial practice and it makes disputes easier to settle, but the rule does not ask for it.
- Rounding to the whole rupee. Also convention. If you do round, show the round-off as its own line rather than quietly adjusting a tax figure — a tax amount that does not reconcile to the rate times the taxable value is what draws a query.
Your logo, bank details and payment terms are all fine to include and none of them are required either.
Where a bill of supply applies instead
If you are registered under the composition scheme, or supplying goods and services that are exempt, you issue a bill of supply rather than a tax invoice — because there is no tax to show. A composition dealer's bill of supply also has to state that they are not eligible to collect tax on supplies. Issuing a tax invoice showing GST when you are not entitled to collect it is a more serious problem than a missing field.
How BahiSathi handles it
The invoice PDF carries every field in the table above. You fill in your business once and pick a customer, and the rest is derived: the HSN or SAC comes from your saved price-list item, the tax heads from the place of supply, the taxable value from the line after its discount, and the serial from your series for that document type and financial year.
The serial is capped at 16 characters by trimming the prefix rather than by producing a number that is over the limit, and it is reserved on our server rather than counted on your phone — so two devices on the same account cannot issue the same number, and there are no gaps to explain later.
This is a plain-language summary of the rule as it stands, not legal advice. Thresholds and HSN digit requirements change; check the current position with your accountant.