Invoices in India: GST Formats & Free Generator
An Indian tax invoice is more than a payment demand — it is the document the GST department uses to verify every rupee of your output tax. Get a field wrong and the buyer cannot claim input tax credit, which slows payment and can surface as a notice months later.
This guide walks through the full invoice anatomy: validity requirements, mandatory fields, tax invoice versus bill of supply, HSN and SAC codes, supporting documents like credit notes, e-invoicing, and the archives you must keep. It ends with a free generator that builds a compliant invoice in under a minute.
Whether you bill ₹4,000 consignments or ₹60 lakh orders, the field set is fixed by law — only the volume changes.
What makes an invoice legally valid in India
A invoice that meets GST law has two properties: it carries every field prescribed in the GST Rules, and it is issued within the time limit from the date of supply. Validity is a question of completeness and accuracy, not of design or print quality.
An invoice that omits the supplier's registered name, the recipient's GSTIN or the tax split is legally defective. The recipient loses the right to claim input tax credit on that document, and the supplier has issued a non-compliant record of its own tax.
Anatomy of a GST tax invoice
Think of the tax invoice as three stacked blocks: the identity block at the top, the supply detail in the middle, and the tax computation at the bottom. The identity block holds names, addresses, GSTINs and the meta — number, date and place of supply.
The middle block itemises goods or services with HSN or SAC codes, and the bottom block splits taxable value into CGST and SGST, or IGST on inter-state supplies, closing with the total in figures and words.
| Slab | Example goods or services | CGST | SGST | IGST |
|---|---|---|---|---|
| 5% | Packed food, footwear below ₹1,000 | 2.5% | 2.5% | 5% |
| 12% | Butter, phones, work contracts | 6% | 6% | 12% |
| 18% | Most services, IT goods, furniture | 9% | 9% | 18% |
| 28% | Luxury and sin goods | 14% | 14% | 28% |
Mandatory fields on every GST invoice
GST Rules lay out a precise checklist of fields, and the portal and the buyer both validate against it. A single blank — an empty HSN, an outdated GSTIN — can void the credit claim.
Take Ramesh Traders of Delhi billing a Delhi retailer ₹1,20,000 of taxable goods at 12%. The tax invoice prints taxable value ₹1,20,000, CGST ₹7,200 and SGST ₹7,200, and closes at ₹1,34,400 — a split that matches the buyer's GSTR-2B without a single query.
- Supplier name, address and GSTIN, plus recipient name, address and GSTIN when the buyer is registered.
- Sequential invoice number and date of issue, tied to the financial year.
- Itemised description, quantity, unit price, taxable value and HSN or SAC code.
- Rate and amount of CGST and SGST, or IGST, line by line and in the total.
- Total value in figures and words, with the supplier's signature.
Tax invoice vs bill of supply
A tax invoice shows GST separately so a registered buyer can take credit; a bill of supply carries no tax lines and grants no credit. Which document you issue is decided by the buyer and the supply, not by preference.
Supplies to unregistered persons, exempt goods and composition-dealer supplies all move on a bill of supply, styled 'composition taxable person' where the scheme applies.
| Point | Tax invoice | Bill of supply |
|---|---|---|
| GST shown | Separately, line by line | Not shown |
| Input tax credit | Claimable by a registered buyer | Not available |
| Used for | Taxable supplies, registered buyers | Exempt goods, unregistered buyers |
| Heading printed | TAX INVOICE | BILL OF SUPPLY |
Invoice formats for B2B, B2C and services
B2B invoices carry the recipient's GSTIN and act as the buyer's credit-taking document; B2C invoices omit the recipient GSTIN but keep every other field. Service invoices add a place-of-supply line and an SAC code, and milestone billing often references a project or work order.
An export of services is marked zero-rated, with the foreign-currency amount and exchange rate printed on the line so the refund file stays self-contained.
Proforma, credit note and debit note
A proforma invoice is a quotation, not a tax document — it states what you will charge without raising a GST liability and without consuming a number from your running series. Send it before the order, and replace it with the real tax invoice once the supply happens.
- Proforma — no tax liability, no series number, replaced by the final bill.
- Credit note — issued when a supply is returned, amended or repriced downward; linked to the original invoice number.
- Debit note — issued when an earlier invoice is repriced upward; also linked to the original document.
- Both notes flow into your GST reconciliation and the buyer's ITC match.
E-invoicing and the Invoice Reference Number
E-invoicing is mandatory for businesses whose aggregate turnover crosses the notified threshold, judged on a past financial year. The document is reported on the GST portal and an Invoice Reference Number is generated before the supply is billed.
Below the threshold an ordinary PDF or printed invoice is fully valid. The limit is revised by notification, so verify the current figure for your turnover band rather than relying on memory.
Digital invoices and the 8-year archive
GST records must be preserved for at least 8 years from the end of the relevant financial year, and digital copies are acceptable so long as they are legible and complete. A dated PDF folder is a legal record, not a convenience.
Save every generated invoice the day it is issued, named with the number and month. When scrutiny asks for a year of bills, the answer is a folder, not a scramble.
Common invoice errors that get invoices rejected
The defects auditors flag most are wrong GSTINs, HSN digits borrowed from a brand name instead of the classification, manual arithmetic that drifts from the slab, and totals that change after rounding. Each one breaks the buyer's GSTR-2B match and stalls payment.
- Unverified GSTIN on the supplier header.
- HSN with the wrong digit count or an invented code.
- Tax totals typed by hand instead of computed.
- No place of supply on an inter-state service invoice.
- Missing amount-in-words line.
Generate a compliant invoice free
The Crafex invoice generator builds this anatomy automatically — identity block, item lines with HSN or SAC, CGST/SGST/IGST splits, totals in figures and words — and downloads a clean PDF, all in the browser with no uploads.
Customer data stays on your device, and each PDF drops straight into the 8-year archive your records require.
How to do it, step by step
- 1
Confirm your GST status
Check whether the supply is taxable and whether you are registered; this decides whether the document is a tax invoice or a bill of supply.
- 2
Fill the identity block
Enter supplier and recipient details with GSTINs, the sequential invoice number and the date of the supply.
- 3
Add the supply lines
Describe each item with quantity, unit price, taxable value and the correct HSN or SAC code.
- 4
Apply the tax split
Compute CGST and SGST for intra-state supplies or IGST for inter-state, and print the total in figures and words.
- 5
Download and archive the PDF
Save the PDF the day it is issued into a dated folder so the 8-year record stays complete.
Frequently asked questions
What happens if a GST invoice misses a mandatory field?+
The buyer cannot claim input tax credit on that document because the credit is matched against those exact fields in GSTR-2B. You will be asked to issue a credit note and a fresh invoice, and repeated defects attract audit queries and penalty provisions under GST law.
Can one invoice combine goods and services?+
Yes. A composite supply is billed on one tax invoice at the principal supply's HSN or SAC and rate. Where goods and services are genuinely separate and independently priced, they appear as separate lines, each with the applicable rate, on the same document, and the total closes with the combined tax.
How soon after a supply must the tax invoice be issued?+
For goods, the invoice is issued before or at the time of removal or delivery. For services, it must be issued within 30 days of the supply, and banks and insurers get 45 days. These prescribed limits are audit-checked, and late invoices complicate the return.
Are digital invoices without a signature valid?+
Yes for practical purposes. A PDF invoice is legally accepted, and GST filings carry digital signatures. Paper invoices still print the signature block, while e-invoices carry the portal-generated IRN as their authentication marker. In all cases the fields, not the signature, determine validity.
Does a bill of supply still need a GSTIN?+
Yes. The bill of supply shows the supplier's GSTIN, name and address, but no tax lines and no credit. Even with no GST charged, the document remains part of the registered supplier's records and must be numbered sequentially within the financial year like any other issue.
Why do buyers reject an invoice for a small amount?+
Because even a ₹500 invoice must carry the full field set. If the GSTIN, HSN or tax split is wrong, the buyer's system flags the credit and the invoice sits unpaid until corrected. The amount never excuses field defects, so keep the smallest bill as strict as the largest.
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Why you can trust this guide
Written by Crafex Finance Desk (GST & Billing Documentation Experts), last reviewed 2026-08-01. We update these guides when statutory rules and formats change. Where Indian regulations apply, we link the official sources below. Verify critical calculations against the current government notifications before relying on them.
A Crafex editorial guide for Indian professionals and businesses.