If your business is registered under GST, the invoices you issue are more than a request for payment. They are the documents your customers use to claim input tax credit, and the records you rely on when you prepare returns or answer a query from the tax department.
The contents of a tax invoice are set out in the CGST Rules, 2017 (Rule 46). You don’t need a particular design or template — what matters is that the required details are present and correct. This guide walks through those details in plain English.
Tax Invoice, Bill of Supply, or Something Else?
A registered business supplying taxable goods or services issues a tax invoice . Two common exceptions use a bill of supply instead, which does not charge or show GST:
- Businesses registered under the composition scheme.
- Suppliers of exempt goods or services (for example, certain unprocessed food items).
Other GST documents cover situations around the invoice: a receipt voucher when you take an advance, and credit or debit notes when the value of a supply changes after the invoice — for example, when goods are returned or a price is revised. A credit note adjusts the original invoice; you should not edit or delete an invoice that has already been issued.
The Details a GST Tax Invoice Must Show
Rule 46 lists the particulars a tax invoice must contain. In practical terms, check that every invoice shows:
- Your business name, address, and GSTIN.
- A consecutive serial number, unique for the financial year. It can be up to 16 characters and may use letters, numbers, hyphens (-), and slashes (/). You can run more than one series — for example, one per branch.
- The date of issue.
- The customer’s name, address, and GSTIN if they are registered.
- For an unregistered customer above a value threshold (₹50,000 at the time of writing): their name and address, and the delivery address with the state name and state code.
- The HSN code for goods or the SAC code for services. How many digits you must show depends on your annual turnover.
- A description of the goods or services.
- Quantity and unit, for goods.
- The total value, and the taxable value after any discount.
- The tax rate and tax amount for each tax that applies — CGST and SGST (or UTGST), or IGST, plus any cess.
- The place of supply with the state name, for inter-state supplies.
- The delivery address, if it is different from the place of supply.
- Whether tax is payable on reverse charge.
- The signature or digital signature of the supplier or an authorised person.
Showing the place of supply on every invoice — not just inter-state ones — is a good habit. It is the single detail that decides whether you charge CGST and SGST or IGST, which our guide to CGST, SGST, IGST and place of supply explains in detail.
How Many Copies, and When to Issue
The rules also set how many copies to prepare:
- Goods: three copies — the original for the buyer, the duplicate for the transporter, and the triplicate for your own records.
- Services: two copies — the original for the customer and the duplicate for you.
For goods, the invoice is generally issued at or before the time the goods are removed or delivered. For services, it is generally issued within 30 days of providing the service, with a longer window for some sectors such as banking and insurance.
Common GST Invoice Mistakes
- Gaps or duplicates in invoice numbers — often caused by keeping separate bill books, or two people billing from the same spreadsheet.
- A wrong or mistyped GSTIN for the customer, which stops them claiming input tax credit.
- Charging CGST and SGST on a sale that is actually inter-state, or IGST on one that is intra-state.
- Missing HSN or SAC codes, or codes with fewer digits than your turnover requires.
- Editing an issued invoice to reflect a return instead of issuing a credit note.
- Tax worked out on the price before discount instead of the taxable value after it.
A Note on E-Invoicing
Businesses whose aggregate turnover is above a threshold notified by the government must also report their business-to-business invoices to the Invoice Registration Portal and obtain an Invoice Reference Number (IRN) and QR code. The threshold has been lowered several times since e-invoicing began, so check the current limit on the official e-invoice portal and with your accountant.
Key Takeaways
- A tax invoice is defined by its contents, not its design — Rule 46 of the CGST Rules lists what it must show.
- Numbering must be consecutive and unique within the financial year; multiple series are allowed.
- Place of supply decides CGST + SGST versus IGST, so record it on every invoice.
- Fix a mistake with a credit or debit note — never by editing an issued invoice.
How BizPro Helps
BizPro stores your GSTIN and state on the business and each customer’s GSTIN in the tax number on their record, numbers invoices automatically without gaps or duplicates per financial year, and prints HSN or SAC codes from each product. Enter the place of supply and BizPro applies CGST + SGST or IGST for you, and returns are handled with credit notes so issued invoices are never edited. See GST billing software and invoicing software for the full picture.