Free tool
GST Invoice Generator
Generate a GST-compliant tax invoice. Pick the seller and buyer states, add line items with HSN / SAC and the GST rate; the calculator routes to CGST + SGST or IGST automatically.
A worked example, end to end
Scenario
A consulting firm in Karnataka invoices a client in Maharashtra for 10 hours of consulting at ₹2,500/hour. SAC 998313. GST at 18%.
Computation
- Supply type. Karnataka → Maharashtra = inter-state, so IGST.
- Taxable value. 10 × ₹2,500 = ₹25,000.
- IGST. 18% × ₹25,000 = ₹4,500.
- Total payable. ₹25,000 + ₹4,500 = ₹29,500.
- If buyer were in Karnataka. CGST 9% (₹2,250) + SGST 9% (₹2,250). Same total.
- Customer ITC. Buyer claims ₹4,500 IGST as input tax credit in their GSTR-3B.
Free download
GST invoice template (Excel).
A formula-driven Excel invoice template with auto CGST/SGST/IGST detection from state codes, HSN dropdown, multi-line support and auto-numbering. For teams that prefer Excel to a web app.
What makes an invoice "GST-compliant"
Rule 46 of the CGST Rules specifies the minimum fields on a tax invoice:
- Supplier name, address and GSTIN.
- Consecutive invoice serial number (unique per financial year).
- Date of issue.
- Recipient name, address and GSTIN (if registered). For unregistered recipients with value over ₹50,000, the recipient's name, address and place of delivery.
- HSN / SAC code (at the right digit count for your turnover).
- Description of goods or services, quantity, unit and total value.
- Rate and amount of tax, split into CGST, SGST or IGST.
- Place of supply with the name of the state for inter-state moves.
- Signature or digital signature of the supplier.
Intra-state vs inter-state
Same-state supply attracts CGST + SGST in equal halves. Cross-state supply attracts IGST at the full rate. The supply type is determined by the place of supply rules (Section 10-13 of the IGST Act).
GST invoice FAQ
Common questions.
Can I issue invoices in any serial format?
The series must be consecutive (no gaps), unique per financial year, and not exceed 16 characters. Letters, digits and hyphens are allowed. You can have multiple series for different branches or supply types but each must be unique within the year.
When is an e-invoice (IRN) required?
For taxpayers with aggregate annual turnover above ₹5 Cr in any preceding financial year, e-invoicing is mandatory for B2B supplies (including exports and SEZ). The invoice JSON is submitted to the IRP, which returns an IRN and a signed QR code. B2C is exempt.
Is a buyer GSTIN mandatory?
No, GSTIN is only required if the buyer is GST-registered. For unregistered buyers, leave GSTIN blank. If the value is above ₹50,000 to an unregistered buyer, the invoice should still capture the buyer's name, address and place of delivery (Rule 46).
How do I show CGST and SGST vs IGST?
Look at the place of supply. If the recipient state equals the supplier state, the supply is intra-state and the GST splits 50:50 into CGST + SGST. If they differ, it is inter-state and the full GST is IGST. The calculator auto-detects this from the two state picks.
What if I sell exempt or zero-rated goods?
Pick 0% as the GST rate. For exports and SEZ supplies (zero-rated), you may issue with a Letter of Undertaking (LUT) and 0% IGST, while still claiming input tax credit. Exempt supplies attract 0% but block ITC on related inputs.
Can I revise an issued invoice?
Tax invoices cannot be edited once issued and reported. To correct, issue a Credit Note (for downward revision) or a Debit Note (for upward revision). These adjust the original tax position in the next GSTR-1 and GSTR-3B.
When should I issue the invoice?
For goods: at or before delivery. For services: within 30 days of providing the service. For continuous supply: at the time payment is due as per contract. Banks and insurers: within 45 days. Late issuance can attract penalties under Section 122.
What is a "bill of supply" vs a "tax invoice"?
A tax invoice is issued for taxable supplies. A bill of supply is issued for exempt supplies or by composition taxpayers (who cannot collect GST). The two cannot be issued for the same supply: pick one based on whether the supply is taxable.
Can a customer claim ITC if my invoice is wrong?
No. The customer's ITC depends on the supplier's GSTR-1 being filed correctly and the data flowing into GSTR-2B. If the invoice has a wrong GSTIN, wrong HSN-rate, or is not reported on time, the customer's ITC is blocked under Rule 36(4) read with Section 16(2)(aa).
How many copies of a tax invoice should I issue?
Three copies for goods: original for the recipient, duplicate for the transporter, triplicate for the supplier. Two copies for services: original for the recipient, duplicate for the supplier. Digital copies count as long as the recipient can preserve them.
Related tools
More GST tools.
- GST CalculatorAdd or remove GST at 0/5/12/18/28%. CGST/SGST or IGST split based on supply type.
- HSN & SAC Code FinderSearch 670+ HSN and SAC codes with GST rates. Needed on every invoice.
- E-Way Bill CalculatorCheck if an e-way bill is required and calculate validity by distance and ODC status.
- GST Late Fee CalculatorLate filing fee + 18% Section 50 interest for delayed GSTR returns.
Invoicing, native to your finance stack.
OneFinOps generates GST invoices, e-invoices, e-way bills, payment links, and reconciles cash receipts against AR. The calculator is for one off; the platform runs the AR desk.