What Rule 46 actually requires
A tax invoice under GST is not a free-form document. Rule 46 of the CGST Rules lists the particulars it has to carry, and an invoice missing one of them is a problem for your customer as much as for you — it is the document their input tax credit rests on.
Your name, address and GSTIN.
Unique and consecutive within the financial year, at most 16 characters, using letters, digits, hyphens and slashes only.
The date the invoice is raised.
Name, address, and GSTIN if they are registered. For an unregistered recipient above ₹50,000 you also need their address and the state.
The classification code for each good or service. How many digits are required scales with your turnover.
What was supplied, how much of it, and in what unit of measure.
The value per line after any discount, before tax is added.
Split into CGST and SGST, or shown as a single IGST line — see below.
The state. This is what decides the split, and it is the field most often left off.
Whether tax is payable on a reverse-charge basis. State it either way rather than leaving it blank.
Of the supplier or an authorised representative. A digital signature is fine.
This page describes the format so you can lay an invoice out correctly. It is not tax advice and does not replace your accountant — thresholds and turnover-linked requirements change, and yours depend on your registration.
The CGST/SGST split, plainly
One rate, two ways of printing it. The deciding factor is the place of supply, not where you are sitting.
| Place of supply | Type | How 18% prints |
|---|---|---|
| Your own state | Intra-state | 9% CGST + 9% SGST |
| Another state or UT | Inter-state | 18% IGST, one line |
The customer pays the same total either way. What changes is which government receives it. Getting this wrong is the single most common fault in a hand-made Indian invoice, which is why the generator asks one question — same state or another state — and prints the right lines from your answer.
A related trap: halve the money, not the rate. Computing 9% twice and rounding each result can leave the two halves a paisa short of the whole, and a reconciliation that is off by one paisa is still off.
When you have to issue it
- Goods: on or before removal or delivery.
- Services: within 30 days of supply — 45 days for banks, insurers and other financial institutions.
- Continuous supply: on or before the due date each statement covers.
Copies
For goods, an invoice is issued in triplicate — original for the recipient, duplicate for the transporter, triplicate for you. For services it is in duplicate. A PDF printed twice satisfies this as well as pre-printed stationery does; the marking is what matters, and you can add it in the notes field.