How to create a GST invoice in India — fields, format and free template

Quick answer: a valid Indian GST invoice (Rule 46 of the CGST Rules) must include: supplier name + GSTIN + address, invoice number (consecutive, unique per FY) + date, buyer name + GSTIN if registered, HSN/SAC code, description / qty / rate / taxable value of each item, CGST + SGST split (intra-state) or IGST (inter-state), total in figures and words, and signature. Get any of these wrong and the buyer can't claim input tax credit — which means they'll likely refuse to pay you.

For freelancers and small businesses, the GST invoice is one of those things that looks simple but trips up beginners constantly. The format is regulated; you can't just use a generic Word template.

Mandatory fields per Rule 46

Every tax invoice for a registered taxpayer must include:

1. Supplier's name, address, GSTIN.
2. Invoice number — consecutive, unique within the FY. Cannot exceed 16 characters. Can use letters, numbers, dashes, slashes.
3. Invoice date.
4. Recipient's name and address. GSTIN is required if the buyer is registered.
5. HSN code (for goods) or SAC code (for services). 4 digits if your turnover is < ₹5 crore, 6 digits if ≥ ₹5 crore.
6. Description / quantity / unit / rate / taxable value for each line item.
7. Tax rate and amount split into CGST + SGST (intra-state) or IGST (inter-state).
8. Total invoice value in figures and words.
9. Place of supply (state) — required for inter-state.
10. Signature of supplier (or digital signature).

Some optional fields commonly added: due date, payment terms, bank account details, ICAI/CA reference for service invoices.

CGST + SGST vs IGST

The supplier's and the place of supply determine which split applies:

• Same state (supplier and buyer both in Karnataka, for example) → CGST + SGST, each at half the GST rate. So 18% becomes 9% + 9%.
• Different states (supplier in KA, buyer in TN) → IGST at the full rate. 18% becomes a single 18% IGST line.

The total tax is identical — only the routing changes. The state government gets the SGST portion in intra-state cases; in inter-state, the destination state gets the SGST equivalent later via an inter-state settlement.

HSN / SAC codes — what they are

• HSN (Harmonised System of Nomenclature) — 4 to 8 digit codes for goods. Internationally standardised.
• SAC (Service Accounting Code) — 6 digit codes for services. India-specific, all start with 99.

Examples:

• 998314 — IT services / web design / app development
• 998313 — IT consulting
• 998391 — Specialised design services
• 9983 — Other professional, technical and business services
• 8517 — Mobile phones
• 6403 — Footwear

If you don't know your HSN/SAC, the GST portal's rate finder is the official source. For small turnover (< ₹5 cr), the 4-digit prefix is enough; you don't need to dig into the full 8-digit code.

Invoice numbering rules

Per Rule 46:

• Consecutive — no gaps. INV-0001, INV-0002, INV-0003... If you cancel an invoice, you can't reuse the number.
• Unique — no duplicates within the same financial year.
• Resets every FY — start fresh on April 1 each year.
• Up to 16 characters including dashes/slashes.
• Alphanumeric with /-_ allowed.

A common pattern: INV-2026-0001 (year + sequence). Or use prefixes for different segments: CONS-2026-001 for consulting, PROD-2026-001 for product sales.

When you don't need to issue a tax invoice

• Composition scheme taxpayers (turnover up to ₹1.5 cr, 1-6% rate) issue a “Bill of Supply”, not a tax invoice. They can't collect or claim GST.
• Exempt supplies — also a Bill of Supply.
• Not registered for GST — if your annual turnover is below ₹20 lakh (₹10 L for special-category states), you don't need to register, and you can't collect GST. Issue a regular plain invoice without GST fields.

Common mistakes that cost your buyer ITC

If your invoice has any of the following errors, the buyer cannot claim input tax credit on it. They'll either refuse to pay or demand a reissued invoice:

• Missing GSTIN of supplier or buyer.
• Wrong place of supply — leads to wrong CGST+SGST vs IGST split.
• Missing HSN/SAC code.
• Calculation error — taxable value × rate ≠ tax shown.
• Invoice issued late — must be within 30 days of supply for services (one month for goods).
• No signature. Even a digital one (PDF with embedded signature) is mandatory.

Reverse charge basics

If you supply notified services to a registered person (legal services to a company, GTA transport, etc.), the buyer pays GST under reverse charge — you issue an invoice without charging GST, marked “GST under reverse charge”. You don't collect GST on these but the buyer self-pays it.

Use the GST Invoice Generator

The GST Invoice Generator creates a Rule-46-compliant invoice in your browser. Fill in supplier and buyer details, add line items with HSN, choose intra-state (CGST+SGST) or inter-state (IGST), and print to PDF. The amount-in-words generator handles Indian lakhs and crores correctly (no “million” or “billion”).

FAQ

Q. Can I generate GST invoices without using accounting software? A. Yes. The legal requirement is the format and content, not the software. A PDF you create from a template / generator is valid as long as it has all the Rule 46 fields. Most freelancers and small consultants do this.

Q. Do I need GSTIN to issue an invoice? A. Only if you're registered. If your turnover is below the threshold, you issue a non-GST invoice (bill of supply) without GSTIN — but you can't collect GST.

Q. What's the time limit to issue an invoice? A. For goods: at the time of supply (delivery / movement). For services: within 30 days of supply (45 days for banks / financial institutions).

Q. Can I email the invoice or do I need a physical copy? A. Email or any electronic delivery is fine. The invoice can be in PDF / soft copy. A physical signed copy is only required if specifically demanded by the buyer.

Q. What about e-invoicing? A. Mandatory if your annual turnover exceeds ₹5 crore (as of 2025). You generate the invoice in your accounting system, upload it to the IRP (Invoice Registration Portal), get an IRN (Invoice Reference Number) and QR code back, then issue the final invoice with those embedded. Below ₹5 cr turnover, traditional invoicing is fine.