GST Invoice Format: Mandatory Fields and a Free Maker

By Neha·Published October 1, 2026

If you are registered under GST, every sale needs a proper bill. Your customer needs it to claim input tax credit, which is the GST they paid that they can set off against their own GST. You need it for your returns. And a bill with missing details can cause trouble for both of you later. The good news is that the GST invoice format is not complicated once you know which fields are required and why.

This guide explains the mandatory fields in plain words, when to charge CGST and SGST and when to charge IGST, and how to make a correct bill for free. It is general guidance, not tax advice. Rules and limits change, so confirm anything specific to your business with your CA.

Short answer: A GST tax invoice must show your name, address and GSTIN, a unique invoice number and date, the customer's details (and GSTIN if they are registered), HSN or SAC codes, a description, quantity and value of each item, the taxable value, the tax rate and amount, the place of supply, whether reverse charge applies, and your signature. Charge CGST plus SGST within your state, and IGST for another state.

What is a GST invoice, and who needs to issue one?

A tax invoice is the bill a GST-registered business issues when it sells taxable goods or services. The rules on what it must contain are set out in Rule 46 of the CGST Rules, 2017. The official text and circulars are on the CBIC GST website.

You issue a tax invoice if you are registered under GST in the regular scheme and you are charging GST. Two common cases are different:

• Composition dealers, who pay tax at a fixed rate on turnover under the composition scheme, cannot charge GST to customers. They issue a bill of supply instead, and must state on it that they are a composition taxable person not eligible to collect tax.
• Exempt goods or services, like certain fresh food items, are also billed on a bill of supply, because no GST is charged.

If you are not registered under GST at all, you cannot charge GST or show it on your bill. Whether you need to register depends on your turnover, what you sell and where. Check the current limits on the GST portal or with your CA.

What are the mandatory fields in a GST invoice format?

Here are the mandatory fields in GST invoice format under Rule 46, in plain words. A correct tax invoice format includes all of these.

A few of these need a short explanation.

Invoice number

The number must follow a running series, like UP/2026-27/001, UP/2026-27/002 and so on. It can have letters, numbers, a hyphen or a slash, up to 16 characters, and it must not repeat within the same financial year. You can run more than one series, for example one per branch, as long as each number is unique. Most businesses start a fresh series each April.

HSN and SAC codes

HSN stands for Harmonised System of Nomenclature, the code system for goods. SAC stands for Services Accounting Code, the code system for services. How many digits you must show depends on your turnover and the type of supply, and those rules have changed over time, so check the current requirement on the GST portal or with your CA.

Reverse charge

Normally the seller collects GST and pays it to the government. Under reverse charge, the buyer pays it instead. This applies only to certain goods, services and situations. Your invoice must say whether reverse charge applies, even when the answer is no.

When do you charge CGST, SGST and IGST?

People often search "CGST SGST IGST" because three tax names on one bill look confusing. The difference depends on one question: are you and your customer's place of supply in the same state?

• Within the same state (intra-state): you charge CGST (central GST) plus SGST (state GST), split equally. In a union territory without its own legislature, UTGST replaces SGST.
• To another state (inter-state): you charge IGST (integrated GST) for the full rate, as one amount.

The total tax is the same either way. Only the split changes. So at an 18% rate, an intra-state bill shows 9% CGST plus 9% SGST, and an inter-state bill shows 18% IGST.

For goods, the place of supply is usually where the goods are delivered. For services, the rules can be more involved, especially for online services, events and customers outside India. If you are unsure, ask your CA before you issue the bill, because charging the wrong type of tax is a common and annoying mistake to fix.

GST rates also change from time to time. Always check the current rate for your HSN or SAC code rather than copying last year's bill.

A worked example: a freelance web designer in Indore

Priya is a freelance web designer in Indore, Madhya Pradesh, registered under GST. She builds two websites in the same month, each for ₹40,000. In this example, assume her service is taxed at 18%. Check the current rate for your own service code.

Client 1 is a clinic in Bhopal, also in Madhya Pradesh. This is intra-state, so she charges CGST and SGST.

• Taxable value: ₹40,000
• CGST at 9%: ₹3,600
• SGST at 9%: ₹3,600
• Total: ₹47,200

Client 2 is a boutique in Surat, Gujarat. This is inter-state, so she charges IGST.

• Taxable value: ₹40,000
• IGST at 18%: ₹7,200
• Place of supply: Gujarat, with its state code
• Total: ₹47,200

Both clients pay the same amount. The difference is where the tax goes and how it appears on the bill. On both invoices, Priya shows her GSTIN, a fresh invoice number from her series, the client's GSTIN if they have one, the SAC code for her service, and "Reverse charge: No".

How to make GST invoice bills correctly, step by step

Here is how to make a GST invoice for a sale, whether you use a tool, a spreadsheet or accounting software.

1. Check your own details. Business name, address and GSTIN, exactly as on your registration.
2. Pick the next invoice number in your series. Never skip or reuse a number.
3. Enter the date you issue the invoice.
4. Add the customer's name, address and GSTIN. Ask for the GSTIN before billing a business customer. The GST portal has a search to check that a GSTIN is valid.
5. Decide the place of supply. Same state means CGST and SGST. Another state means IGST.
6. Add each item with its description, HSN or SAC code, quantity, unit and rate.
7. Apply any discount before tax, so the taxable value is correct.
8. Add the tax rate for each line and check the tax amounts.
9. Mark reverse charge as yes or no.
10. Sign it, by hand or digitally, and keep a copy.

The free GST Invoice and Quotation Maker does the working for you. You enter your details and items, choose same state or other state, and it splits the tax into CGST and SGST or IGST, adds a tax summary by rate, writes the total in words the Indian way, and lets you save it as a PDF. It runs in your browser, so your figures are not sent anywhere.

What does a simple GST bill format look like?

Many shopkeepers search for a GST bill format they can copy. The layout is less important than the content, but a clear bill usually runs in this order:

1. Top: the words "Tax Invoice", your business name, address and GSTIN.
2. Invoice details: invoice number, date, place of supply and reverse charge.
3. Bill to: customer name, address and GSTIN. Ship-to address if different.
4. Item table: description, HSN or SAC, quantity, unit, rate, discount, taxable value, tax rate and tax amount.
5. Totals: taxable value, CGST and SGST or IGST, any round-off, and the grand total in figures and in words.
6. Bottom: bank or UPI details, terms, and your signature.

For goods, the rules also say how many copies to make: usually an original for the buyer, a duplicate for the transporter and a triplicate for you. For services, an original and a duplicate. Your CA can confirm what applies to you.

Invoices, quotations and payment reminders

A quotation is not a tax invoice. It is a price offer before the sale, and it does not go into your GST returns. The GST Invoice and Quotation Maker makes both. If you sell SEO or marketing services, the Quotation Maker builds a detailed SEO quotation with GST, discount and a client acceptance block.

Before you fix your prices, the Profit Margin Calculator shows the right price with GST and your real profit on each sale. And when a customer is late, the Payment Reminder Writer drafts polite WhatsApp and email reminders with your UPI or bank details.

What about e-invoicing?

E-invoicing means registering a B2B invoice on the government's Invoice Registration Portal, which gives it a unique number and a QR code. It is compulsory only for businesses above a certain turnover, and that limit has been lowered several times. Check the current limit on the GST portal or with your CA. If you are below it, a correctly filled tax invoice like the one described here is what you need.

What to do this week

If you issue bills by hand or from an old template, spend an hour checking your GST invoice format against the list above.

• Compare your current bill with the mandatory fields table and note anything missing.
• Set up a clean invoice number series for this financial year.
• Look up the correct HSN or SAC code and current GST rate for your main products or services.
• Add a "Reverse charge: Yes or No" line and a place of supply line to your bill.
• Try the free GST Invoice Maker for your next bill and save the PDF.
• Book fifteen minutes with your CA to confirm your codes, rates and e-invoicing status.

Once your bills are sorted, it is worth making sure customers can find you online too. Our guides to local SEO for small business and website cost in India are good next reads.

Frequently asked questions

Is there one official GST invoice format I must use?

No. The law lists the details a tax invoice must contain, but it does not fix a design or layout. You can use your own template, accounting software or a free online maker, as long as every mandatory field is there and correct. Many businesses add their logo, bank details and terms, which is fine as long as nothing required is missing.

Can I make a GST invoice without GST registration?

No. Only a GST-registered business can charge GST and issue a tax invoice showing GST. If you are not registered, you can still give customers a simple bill or receipt, but it must not show any GST amount. Whether you need to register depends on your turnover, what you sell and where you sell. Check the current rules on the GST portal or with your CA.

What is the difference between CGST, SGST and IGST?

CGST goes to the central government and SGST to the state government. Both are charged together, split equally, when the sale stays within one state. IGST is charged as one amount when goods or services go to another state, and the centre then shares it with the destination state. The total rate is the same. Only the split on the bill changes.

What is a bill of supply?

A bill of supply is used instead of a tax invoice when no GST is charged. Composition dealers use it, because they cannot collect GST from customers, and they must state on it that they are a composition taxable person. Businesses selling exempt goods or services also use it. It has most of the same details as a tax invoice, but no tax amounts.

Can I reset invoice numbers every year?

Yes, most businesses start a fresh series each financial year, from April. The rule is that each invoice number must be unique within the financial year, consecutive in its series, and no longer than 16 characters. Including the year in the number, like INV/2026-27/001, makes it clear and avoids clashes with last year's bills.

Do I need to sign every GST invoice?

The rules require the signature or digital signature of the supplier or an authorised representative. Printed invoices are usually signed by hand or stamped and signed. For invoices sent electronically, a digital signature is used, and there are specific provisions for e-invoices. If you issue bills by email or WhatsApp, ask your CA which form of signature is right for you.