GST invoice format: what a tax invoice must show (with a free template)

A GST invoice with a missing detail can cost your buyer their input tax credit and cost you a difficult conversation. This post walks through the GST invoice format: what a tax invoice must show, when to issue a bill of supply instead, how many HSN digits and characters you may use, and whether e-invoicing applies to you. At the end you can make your own invoice with our free template. This is general information, not tax advice: check rates, codes and your own case with your CA.

When you must issue a tax invoice

Under section 31 of the CGST Act, a registered business that makes a taxable supply issues a tax invoice. For goods, that is before or at the time the goods are removed or delivered. For services, Rule 47 gives you 30 days from the date of supply, or 45 days for insurers, banks, financial institutions and NBFCs.

Two practical rules sit alongside this. If a sale is under ₹200 and the buyer is not registered and does not ask for an invoice, you may issue one consolidated tax invoice at the end of the day for all such sales. And Rule 48 asks for goods invoices in three copies, marked original for recipient, duplicate for transporter and triplicate for supplier, and for service invoices in two.

What Rule 46 asks a tax invoice to show

Rule 46 of the CGST Rules is the checklist. A tax invoice must show:

• Your name, address and GSTIN.
• A consecutive serial number of up to 16 characters, in one or more series, using letters, numbers, hyphens or dashes and slashes, unique for the financial year.
• The date of issue.
• The buyer's name, address and GSTIN, if the buyer is registered.
• For an unregistered buyer, when the taxable value is ₹50,000 or more: the name, address, delivery address, and the State's name and code.
• The HSN code for goods, or the accounting code (SAC) for services.
• A description, and the quantity and unit for goods.
• The total value and the taxable value after any discount.
• The rate and amount of each tax: CGST and SGST (or UTGST), or IGST, and any cess.
• The place of supply, with the State's name for a supply between States, and the delivery address if it differs.
• Whether tax is payable on reverse charge.
• Your signature or digital signature, or that of an authorised representative.

Tax invoice, bill of supply or proforma: which one

Not every sale gets a tax invoice. The type of document depends on who you are and what you sell.

• Tax invoice: a registered business making a taxable supply. It shows the GST charged, and a registered buyer uses it to claim input tax credit.
• Bill of supply: a registered business supplying exempt goods or services, or paying tax under the composition scheme, issues this instead, with no GST on it (section 31(3)(c), with the details in Rule 49). A composition seller must print "composition taxable person, not eligible to collect tax on supplies" at the top, under Rule 5.
• Quotation or proforma invoice: tells the buyer what they will pay before the supply. It is not a tax invoice, so issue the tax invoice when you supply.

B2B and B2C invoices: what changes

When you sell to a registered business (B2B), the buyer's GSTIN is the detail that matters most. Under section 16(2) of the CGST Act, the buyer can claim input tax credit only when it holds your tax invoice and you have reported that invoice in your GSTR-1, so it reaches them. A typing error in their GSTIN can hold up their credit, and your payment with it.

When you sell to a consumer (B2C), there is no GSTIN to show. The delivery address and State come into play once the taxable value reaches ₹50,000, and the end-of-day consolidated invoice is allowed for sales under ₹200.

In both cases the tax type follows the States. When you and the place of supply are in the same State, charge CGST plus SGST at equal rates, half each. When they are in different States, charge IGST at the full rate. Since 22 September 2025, after the 56th GST Council meeting, the main rates are 5% and 18%, with 40% for a short list of goods such as pan masala, tobacco and aerated drinks. To split a price or take GST out of one, use our GST Calculator.

HSN digits, invoice numbers and e-invoicing

HSN digits. Under Notification 78/2020-Central Tax, from 1 April 2021, a business with aggregate turnover of up to ₹5 crore in the previous financial year shows 4 digits of the HSN code, and may leave it off invoices to unregistered buyers. Above ₹5 crore, every tax invoice shows 6 digits.

Invoice numbers. "SE/26-27/0148" has 13 characters and fits. "SHARMAELEC/2026-27/000148" has 25 and does not. Spaces, hashes and underscores are not in the allowed list. If two counters or branches bill at once, give each its own series, such as A/26-27/001 and B/26-27/001, so no number repeats in the year.

E-invoicing. Since 1 August 2023, under Notification 10/2023-Central Tax, a business whose aggregate turnover exceeded ₹5 crore in any financial year from 2017-18 must report its invoices to registered buyers, and its exports, to the Invoice Registration Portal and print the IRN and QR code it gets back. Some sectors are exempt. Rule 48 says an invoice that such a business issues any other way is not treated as an invoice. Since 1 April 2025, a GSTN advisory also stops businesses with turnover of ₹10 crore or more from reporting an invoice more than 30 days after its date.

Worked example: Sharma Electricals, Indore

Sharma Electricals is a made-up shop registered in Madhya Pradesh, with ₹3 crore of turnover last year. It is below ₹5 crore, so it shows 4 HSN digits and does not issue e-invoices. Here are three sales of fittings taxed at 18% in this example.

The third sale is to a consumer, so the 4-digit HSN code may be left off, though showing it does no harm. Every invoice carries the reverse charge line ("No" here), the signature and a number from the shop's series, such as SE/26-27/0148.

Common invoice errors to catch before you send

Most invoice problems are small and repeated on every bill, because they live in the template. Look for these:

1. Numbers that break the rule: more than 16 characters, symbols such as # or spaces, or the same number used by two counters.
2. The wrong tax type: IGST on a sale within your State, or CGST and SGST on a sale to another State.
3. No place of supply on a sale between States.
4. Too few HSN digits for your turnover, or a code typed from memory.
5. No reverse charge line, even when the answer is "No".
6. Tax or totals that do not add up after a discount or rounding.
7. A proforma sent as the final bill, or GST charged by a composition seller.

To check an invoice you have already made, type its details into our GST Invoice Checker. It lists the Rule 46 details that are missing, tests the invoice number and the GSTIN format, checks the HSN digits your turnover needs, says whether the sale needs CGST and SGST or IGST from the two States, and checks that the tax and total add up (within ₹1, our check). It checks the GSTIN's format only, not whether it is registered, and it does not cover e-invoicing, bills of supply or credit notes.

Make your invoice with the free template

Our GST Invoice and Quotation Generator makes a tax invoice, bill of supply, quotation or proforma invoice on A4:

1. Fill in your business once: name, address, GSTIN, State, bank details and logo. They stay in your browser for next time.
2. Add the buyer, the place of supply if it differs from the buyer's State, and each item with its HSN or SAC code, quantity, rate, discount and GST rate. The tool works out CGST and SGST or IGST, takes discounts off before GST and writes the total in words in lakh and crore.
3. Fix what its Rule 46 checks flag, then print or save a PDF and move to the next number.

It does not do e-invoicing, so a business above ₹5 crore must still generate the IRN through the portal. For an advance, a registered business issues a receipt voucher under section 31(3)(d); our Payment Receipt Maker makes a plain payment receipt, not a receipt voucher.

Your next step

Open your last three invoices and check them against the list above, or run one through the GST Invoice Checker. Fix the template once, and every new bill starts from the right layout. If you send invoices by email and customers say they never arrive, read why business emails land in spam. More free tools for GST and small business paperwork are on our free tools page.