GST Invoice Format in India: Every Mandatory Field Explained (with a Sample)

A valid GST tax invoice must show your name, address and GSTIN, a unique invoice number and date, the buyer's details (and GSTIN if they are registered), a description of what you sold with its HSN or SAC code, the taxable value, the tax rate and tax amount on separate lines (CGST + SGST, or IGST), and the place of supply. If any of these are missing or wrong, your buyer may not get input tax credit (ITC), and your GSTR-1 can end up not matching their records.

Below is every field in plain words, a sample invoice, and the mistakes we see most often.

The mandatory fields on a GST tax invoice#

The fields come from the invoice rules under the CGST Rules (Rule 46). Your CA will know the details. Here is the working list for a normal B2B or B2C tax invoice:

1. Supplier's name, address and GSTIN. Your legal name exactly as it appears on your GST registration. If you have a trade name, you can show that too.
2. Invoice number. A running serial number, unique for the financial year. It can use letters, numbers, a hyphen (-) and a slash (/), up to 16 characters. For example: DL/24-25/0147.
3. Date of issue.
4. Recipient's name and address. If the buyer is registered, their GSTIN too.
5. For unregistered buyers above a certain value: their name, address, delivery address, and state name and code. (Your CA can confirm the current value limit for this.)
6. HSN code (goods) or SAC code (services). How many digits you need depends on your turnover. Check the current rule on the GST portal or with your CA.
7. Description of goods or services.
8. Quantity and unit (for goods), for example 50 NOS or 120 KGS.
9. Total value of the goods or services.
10. Taxable value, after any discount.
11. Tax rate and tax amount, shown separately for CGST, SGST/UTGST, IGST and cess, whichever apply.
12. Place of supply, with state name, for inter-state supplies. In practice, show it on every invoice.
13. Delivery address, if it is different from the place of supply.
14. Whether tax is payable on reverse charge (a simple "Reverse charge: Yes/No" works).
15. Signature or digital signature of you or an authorised person.

If your turnover means you fall under e-invoicing, your B2B invoices also need an IRN and QR code from the Invoice Registration Portal. Check the current turnover limit on the GST portal, as it has been lowered a few times.

One more thing. If you are under the composition scheme, or you only sell exempt goods or services, you issue a bill of supply, not a tax invoice. A bill of supply shows no tax.

CGST + SGST or IGST: it depends on place of supply#

This is the field people get wrong most often. The rule is simple:

• Your state and the place of supply are the same → charge CGST + SGST (or CGST + UTGST in a union territory like Chandigarh).
• They are different → charge IGST.

For goods, the place of supply is usually where the goods are delivered. For most services to a registered business, it is usually the buyer's location. Some services, like those linked to property or events, have their own rules. Ask your CA if you are unsure.

Say you run a design agency in New Delhi and bill ₹50,000 for a brand identity project at 18% GST:

The total is the same. But the split matters. If you charge CGST + SGST to the Mumbai client, the tax goes to the wrong place, and the client may not be able to claim ITC. Fixing it usually means a credit note and a fresh invoice.

Always show each tax on its own line. Don't just write "GST 18%: ₹9,000" on an intra-state invoice.

A sample GST tax invoice#

Here is a simple service invoice from a Delhi agency to a client in Pune. You can copy the structure.

TAX INVOICE

Pixelworks Studio
2nd Floor, 14 Lajpat Nagar II, New Delhi 110024
GSTIN: 07ABCDE1234F1Z5
State: Delhi (Code 07)

Invoice No: PWS/24-25/0089        Date: 12-08-2024
Place of Supply: Maharashtra (27)  Reverse Charge: No

Bill To:
Sahyadri Foods Pvt Ltd
Plot 22, Hinjewadi Phase 1, Pune 411057
GSTIN: 27PQRST5678K1Z2

#  Description                  SAC     Qty  Rate      Amount
1  Website redesign (Phase 1)   998314  1    ₹80,000   ₹80,000
2  Social media creatives (20)  998361  1    ₹20,000   ₹20,000
                                     Less discount     ₹5,000
                                     Taxable value     ₹95,000
                                     IGST @ 18%        ₹17,100
                                     Invoice total     ₹1,12,100

Amount in words: Rupees One Lakh Twelve Thousand One Hundred only

For Pixelworks Studio
(Authorised Signatory)

The GSTINs above are made up for illustration. Use the right SAC codes for your own services; the ones shown are examples only.

A few things to notice:

• The GSTIN state code (07 for Delhi, 27 for Maharashtra) matches the address.
• Place of supply is Maharashtra, so it is IGST, not CGST + SGST.
• The discount comes off before tax is worked out.
• The invoice number has the financial year in it, so the series restarts cleanly every April.

Common mistakes that cause trouble in GSTR-1#

These are the errors that show up when your CA files GSTR-1 or when your buyer checks their GSTR-2B.

• Wrong or mistyped buyer GSTIN. The invoice goes to the wrong taxpayer, or gets rejected. Your buyer won't see it and will chase you for their ITC.
• B2B invoice filed as B2C. If you forget the buyer's GSTIN, the sale lands in the B2C section and the buyer gets no credit.
• Wrong tax type. CGST + SGST charged on an inter-state sale, or IGST on a local one.
• Skipped or repeated invoice numbers. Two invoices both numbered 0147, or a jump from 0147 to 0152 with no explanation. Keep one clean series per financial year (you can have separate series, like one per branch, as long as each is consistent).
• Missing or wrong HSN/SAC. GSTR-1 has an HSN summary table, and missing codes cause errors.
• Editing an issued invoice. Once an invoice is sent and reported, don't change it. Issue a credit note (or debit note) instead.
• Rounding differences. Tax worked out per line vs on the total can differ by a rupee or two. Pick one method and stick to it.
• Invoices issued late. There are time limits for issuing an invoice, especially for services. Ask your CA what applies to you.

A small tip: before month-end, ask your CA for a quick list of B2B invoices with GSTINs. Matching them early saves a lot of back-and-forth with clients later.

How invoicing software fills these fields for you#

Making invoices in Word or Excel works when you send five a month. At fifty, the mistakes above start creeping in. Good invoicing software takes care of most of them:

• Your details and GSTIN are saved once and printed on every invoice.
• Invoice numbers run in sequence automatically, with no gaps or repeats.
• Client GSTIN and state are saved with the client, so you don't retype them.
• CGST + SGST or IGST is picked from your state and the place of supply, and shown on separate lines.
• HSN/SAC codes are saved with each product or service.
• Credit notes are linked to the original invoice instead of editing it.
• GSTR-1 data can be exported for your CA, so nobody re-enters invoices by hand.

Clyrix GST invoicing does this for Indian SMBs. Invoices show CGST, SGST and IGST explicitly, you can issue credit notes, record payments against projects, collect online payments through Razorpay, raise export invoices (LUT or IGST), and export GSTR-1 data your CA can use. There is a 14-day free trial with no card needed. See pricing if you want to try it.

Whatever tool you use, the checklist above is what matters. If every invoice has these fields right, your CA's job gets easier, your clients get their credit on time, and a GST check holds no surprises.