How to Write a GST Bill — and How to Generate an Invoice Without GST

You've just completed a project and now need to send an invoice. But one question stops you: should this be a GST bill — or not? And if it is, what exactly needs to go on it?

This guide answers both questions clearly: how to write a proper GST invoice, and when — and how — to issue an invoice without GST at all.

Which Countries Use GST?

GST — Goods and Services Tax — is used in several countries, but the rules, rates, and invoice requirements differ significantly between them.

The main GST countries are:

This article focuses on India's GST system — the most complex of the group, and the one people most commonly search for when asking how to write a GST bill. The CGST Act, 2017 governs the rules, formats, and penalties covered below.

If you are based in Australia, Canada, Singapore, or New Zealand, the core invoicing logic is similar — but the specific fields, thresholds, and tax codes differ. Check your local tax authority's guidelines for country-specific requirements.

What Is a GST Bill?

A GST bill (also called a GST invoice or tax invoice) is a document issued by a GST-registered business at the time of sale. It records the transaction, shows the applicable GST rate, and allows the buyer to claim an Input Tax Credit (ITC) on purchases.

This last point matters. Without a valid GST invoice, your business client cannot claim back the GST they paid. That makes the invoice format a practical concern for both sides — not just a legal formality.

A GST bill is not the same as a regular invoice. It must contain specific mandatory fields defined under the GST Act. A plain invoice or receipt will not qualify.

Who Needs to Issue a GST Invoice?

You must issue a GST bill if:

• Your annual turnover exceeds ₹40 lakh (~$43,000) for goods, or ₹20 lakh (~$21,500) for services — or ₹10 lakh (~$10,750) in special category states
• You are voluntarily registered for GST, even below the threshold
• You are selling to a GST-registered business that will claim ITC

You do not need a GST invoice if:

• You are an unregistered supplier below the turnover threshold
• You are selling GST-exempt goods or services (e.g. fresh produce, educational services, healthcare)
• You are exporting goods or services (zero-rated — covered separately below)

If you're unsure whether you're required to register, the GST portal has a self-assessment tool. When in doubt, check with a CA or tax professional — incorrect registration (or non-registration) both carry penalties.

How to Write a GST Bill: Step by Step

A valid GST tax invoice must include the following elements under the CGST Act, 2017:

1. Label It Correctly

The document must be titled "Tax Invoice". This is not optional. A document labeled "Invoice" or "Bill" without the word "Tax" does not meet GST requirements.

2. Your Business Details

• Your legal name or trade name
• Your complete address
• Your GSTIN (Goods and Services Tax Identification Number) — 15 digits, starting with your state code

3. Invoice Number and Date

• A unique, sequential invoice number — it must follow a running series and cannot be repeated within a financial year
• The date of issue

4. Buyer Details

• Name, address, and GSTIN of the recipient (for B2B transactions)
• For B2C sales above ₹2.5 lakh (~$2,700), the buyer's name and address are also required
• Place of supply — the state where the goods/services are delivered

5. Description of Goods or Services

Be specific. "Consulting services" is acceptable. "Work done" is not.

For goods: include the HSN code (Harmonised System of Nomenclature). For services: include the SAC code (Services Accounting Code).

6. Quantity and Unit Price

• Quantity (for goods)
• Unit of measurement
• Unit price before GST

7. GST Breakdown

This is the part most people get wrong. You must show:

Each must be shown separately with its rate and amount. You cannot combine them into a single "GST" line.

8. Total Amount

• Taxable value (before GST)
• Total GST amount
• Total invoice value (in figures and words)

9. Signature

A digital or physical signature of the supplier or their authorised representative. Unlike invoices in the EU or US, GST invoices in India are expected to be signed — though e-signatures are accepted.

GST Invoice Example

Here is what a correctly structured GST bill looks like:

In this example, IGST applies because the supplier is in Karnataka and the buyer is in Maharashtra — an inter-state transaction.

TAX INVOICE

Supplier: Meridian Design Studio
Address: 14, Koramangala, Bengaluru – 560034
GSTIN: 29AABCM1234A1ZX

Invoice Number: INV-2025-042
Date: 10 April 2025

Bill To:
Next Solutions Pvt. Ltd.
22, Andheri East, Mumbai – 400069
GSTIN: 27AADCN5678B2ZP

Place of Supply: Maharashtra (27)

─────────────────────────────────────────────
Service               SAC     Qty  Unit Price
─────────────────────────────────────────────
Brand Identity Design 998399   1    ₹50,000.00 (~$538)
─────────────────────────────────────────────

Taxable Value:                 ₹50,000.00 (~$538)
IGST @ 18%:                     ₹9,000.00 (~$97)
─────────────────────────────────────────────
Total Amount Due:              ₹59,000.00 (~$635)
(Rupees Fifty-Nine Thousand Only)

Payment Due: 24 April 2025

Authorised Signatory: [Signature]

If you'd rather not build this from scratch, InVault is a free online invoice builder that handles the GST fields, tax breakdown, and formatting automatically — so you can fill in your details and download a ready-to-send PDF in a few minutes.

How to Generate an Invoice Without GST

This is where things get simpler — but also more misunderstood.

You can issue an invoice without GST in three situations:

1. You Are Not Registered for GST

If your turnover is below the registration threshold and you are not voluntarily registered, you simply cannot charge GST — and should not. Charging GST without a valid GSTIN is illegal.

In this case, issue a regular invoice. Do not add a GST line, do not mention GSTIN, and do not label the document "Tax Invoice."

2. You Are Selling GST-Exempt Goods or Services

Some goods and services are fully exempt from GST: fresh fruits and vegetables, milk, eggs, educational services, healthcare, and several others. For these, no GST is applicable — even if you are a registered business.

Issue a regular invoice without any GST breakdown. It is good practice to note "GST Exempt Supply" on the document.

3. You Are Exporting Goods or Services

Exports are zero-rated under GST. This means GST applies at 0% — which is functionally the same as no GST for the recipient.

For exports, issue a Tax Invoice (yes, still required) with IGST at 0% or with a note stating "Supply Meant for Export on Payment of IGST" or "Supply Meant for Export Under Bond/LUT Without Payment of IGST."

What to Include on an Invoice Without GST

Even without GST, a professional and legally sound invoice still needs key information:

• Your name / business name and address
• Invoice number and date
• Client name and address
• Clear description of goods or services
• Quantity and unit price
• Total amount due
• Payment terms and due date

What you leave out: GSTIN, HSN/SAC codes, tax breakdown, and the "Tax Invoice" label.

Label the document simply as "Invoice." This is not a downgrade — it's legally correct for your situation.

Common Mistakes to Avoid

Charging GST without being registered. Even if you think it looks more professional, collecting GST without a valid GSTIN is a serious offence under the GST Act.

Using "Tax Invoice" when unregistered. Only GST-registered businesses can issue Tax Invoices. Using this label when unregistered creates legal exposure.

Missing or wrong GSTIN. A typo in the GSTIN invalidates the invoice for ITC purposes. Always verify — your client's finance team certainly will.

Applying wrong tax type (CGST/SGST vs. IGST). This is one of the most common errors for businesses operating across state lines. The place of supply determines which tax applies — not where you are based.

Vague service descriptions. Avoid writing "Services rendered" or "Work completed." Tax officers and clients both expect specificity. Write what you actually did.

Missing SAC or HSN code. Registered businesses with turnover above ₹5 crore (~$53,800) must include the full 6-digit HSN/SAC code. Below that threshold, 4 digits are sufficient for goods.

Quick Checklist

Use this before sending any invoice:

GST Tax Invoice:

• Labelled "Tax Invoice"
• Your GSTIN included and correct
• Sequential invoice number
• Place of supply stated
• HSN/SAC code included
• CGST+SGST or IGST shown separately (not combined)
• Total in figures and words
• Signed

Invoice Without GST (Unregistered or Exempt):

• Labelled "Invoice" — not "Tax Invoice"
• No GSTIN, no GST line items
• Clear description of goods/services
• Invoice number, date, payment terms
• Your name and address, client name and address

Frequently Asked Questions

Can I issue a GST invoice if I'm not registered? No. Issuing a GST tax invoice without a valid GSTIN is illegal under the GST Act and can attract penalties. If your turnover is below the threshold, issue a regular invoice instead.

What if my client asks for a GST invoice but I'm not registered? Explain that you are an unregistered supplier. Some clients will accept this; others may require you to register. If the volume of work justifies it, voluntary GST registration is an option.

Is a proforma invoice the same as a GST tax invoice? No. A proforma invoice is a preliminary document sent before work begins or before final billing. It cannot be used to claim ITC and is not a valid tax document for GST purposes.

What is the time limit for issuing a GST invoice? For services: within 30 days of the date of supply. For banking and insurance companies: within 45 days. For goods: at the time of removal or delivery.

Do I need to send a GST invoice for every payment? For B2B transactions: yes, always. For B2C transactions below ₹200 (~$2): you may issue a consolidated invoice at the end of the day instead of individual invoices.

Getting the invoice type right — GST or non-GST — is less about complexity and more about knowing which category you fall into. Once that's clear, the format follows naturally.