Invoice Formats · GST-compliant
Invoice format guide — GST invoice, tax invoice, proforma, export.
Every mandatory field under Rule 46 of the CGST Rules, explained with examples. Learn what your Excel invoice needs to include, or skip the spreadsheet and generate GST-correct invoices automatically in TatvaBooks.
- Reviewed June 2026
- 8 min read
- CA Anil Agarwal
Why your invoice format matters
An invoice is not just a payment request — under GST, it is a legal tax document. The format must carry 16 mandatory fields prescribed by Rule 46 of the CGST Rules. A missing field means the recipient cannot claim Input Tax Credit (ITC), and an e-Invoice-mandated supplier risks rejection at the IRP. Whether you use Excel, Word or cloud software, the structure must be right.
Below we break down four invoice formats covering the most common scenarios — GST invoice, tax invoice in Excel, proforma invoice and export invoice — each explaining the fields you need and when to use it.
GST Invoice Format
Standard B2B and B2C sales within India under the GST regime. This is the most common invoice format for registered taxpayers.
Key fields
- Supplier GSTIN and address
- Invoice number and date
- Buyer GSTIN and address (B2B)
- HSN/SAC code per line item
- Quantity, rate and taxable value
- CGST + SGST or IGST (rate and amount)
- Place of supply with state code
- Total invoice value in words and figures
- Reverse charge indicator (Y/N)
Tax Invoice Format in Excel
For small businesses that maintain invoices in Excel before moving to dedicated software. The Excel format mirrors Rule 46 requirements and can be printed as a PDF.
Key fields
- Auto-calculated tax columns (CGST, SGST, IGST)
- HSN/SAC code lookup column
- Running invoice serial number
- Discount column (pre-tax)
- Total in words (formula-generated)
- Place of supply dropdown
Proforma Invoice Format
A preliminary invoice sent before the actual supply — commonly used for quotations, advance payment requests, customs clearance for imports, and letters of credit. Not a tax document.
Key fields
- Marked clearly as 'Proforma Invoice'
- Seller and buyer details
- Itemised description with quantity and rate
- Estimated taxes (GST breakup if applicable)
- Payment terms and validity period
- Delivery terms (Incoterms for exports)
- Bank details for advance payment
Export Invoice Format
For zero-rated supplies under GST — exports with payment of IGST or under LUT (Letter of Undertaking). Must comply with Customs requirements and link to shipping bill.
Key fields
- Marked as 'Supply meant for export on payment of IGST' or 'under LUT'
- Buyer details with country
- Port of loading and destination
- Shipping bill number and date (post-shipment)
- Currency of transaction (e.g. USD, EUR)
- HSN code (mandatory, 8-digit for exports)
- IGST amount or 'Zero-rated under LUT'
- AD code and bank details
Stop formatting invoices by hand.
TatvaBooks fills GSTIN, HSN and place of supply, calculates CGST/SGST/IGST line by line, and numbers every invoice in sequence — at the point of billing. Unlimited invoices, free on the Solo plan.
Credit Note Format
A credit note is issued when a tax invoice needs to be corrected — goods returned, excess amount charged, or a post-supply discount given. Under Section 34 of the CGST Act, the credit note must reference the original invoice number and date, and the GST adjustment must be reported in the return for the month in which the credit note is issued (before 30 November of the next financial year).
Or skip the spreadsheet — generate credit notes in TatvaBooks linked to the original invoice, with GST auto-adjusted and the entry posted to your books.
What must a GST invoice include? (Rule 46, CGST Rules)
Every tax invoice issued by a registered person must contain the following fields. Miss any one of these and the invoice is not a valid tax document — the buyer's ITC claim fails.
| Mandatory field | CGST Rule reference |
|---|---|
| Supplier name, address and GSTIN | Rule 46(a) — legal name and 15-digit GSTIN of the registered person making the supply. |
| Invoice number (sequential, unique per FY) | Rule 46(b) — consecutive serial number, unique for a financial year, containing only alphabets, numerals and special characters (hyphen/dash). |
| Date of issue | Rule 46(c) — date of issue of the invoice. |
| Recipient name, address and GSTIN (B2B) | Rule 46(d) — if the recipient is registered, the name, address and GSTIN; if unregistered, name, address, state and state code. |
| HSN code of goods / SAC code of services | Rule 46(e) — mandatory for all taxpayers; 4/6/8 digit depending on turnover slab. |
| Description of goods or services | Rule 46(f) — clear description sufficient to identify the supply. |
| Quantity and unit | Rule 46(g) — quantity in applicable unit (e.g. KGS, NOS, MTR) for goods. |
| Total value of supply (before tax) | Rule 46(h) — taxable value of the supply, taking into account any discount. |
| Tax rate and amount (CGST, SGST/UTGST or IGST) | Rule 46(i–k) — rate of tax (central, state/UT, integrated) and the tax amount for each. |
| Place of supply (with state code) | Section 10 of the IGST Act — determines whether CGST+SGST or IGST applies. |
| Whether tax is payable on reverse charge | Rule 46(p) — indicate if the tax is payable under reverse charge mechanism. |
| Signature or digital signature of the supplier | Rule 46(q) — signature or digital signature of the supplier or authorised representative. |
For turnover above ₹5 crore, the invoice also needs an IRN and QR code (e-Invoice) — generated by the Invoice Registration Portal at the time of issue.
HSN codes on invoices — is it mandatory?
Yes. Since 1 April 2021, all registered taxpayers must mention HSN/SAC codes on invoices. Taxpayers with turnover up to ₹5 crore use 4-digit codes; above ₹5 crore use 6-digit codes. For exports, 8-digit HSN is standard. Use our HSN code finder to look up the right code for your goods or services.
Excel invoice vs cloud invoicing software
Excel works for very small businesses with a handful of invoices per month. But it breaks down quickly:
- Tax calculation errors — wrong CGST/SGST vs IGST split when the place of supply changes.
- Duplicate serial numbers — no built-in sequence enforcement.
- No e-Invoice support — you cannot generate an IRN from Excel without separate API tooling.
- No return integration — GSTR-1 data must be re-keyed manually.
TatvaBooks handles all of this at the point of billing — GST is calculated line by line, HSN codes are set at the item level, invoice numbers are sequential, and your sales flow into GSTR-1 workings automatically. The Solo plan is free with unlimited invoices.
Frequently asked questions
What is the correct invoice format under GST?
Can I use an Excel invoice format for GST billing?
What is the difference between a tax invoice and a bill of supply?
Is HSN code mandatory on every invoice?
What is a proforma invoice and is it legally valid?
How is an export invoice different from a regular GST invoice?
What happens if my invoice is missing mandatory fields?
Can TatvaBooks generate invoices in the correct GST format?
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