Complete guide with mandatory fields, format rules, CGST/SGST/IGST calculation and a free template — updated for 2025.
Create GST Invoice Free →A GST invoice is a tax document issued by a GST-registered business for every taxable supply of goods or services. It serves as legal proof of the transaction, enables the buyer to claim Input Tax Credit (ITC), and is the basis for your GST return filing. Getting it right matters — missing mandatory fields can lead to ITC rejection for your buyer and penalties for you.
| Field | Required? | Details |
|---|---|---|
| Supplier name & address | Required | Full legal name as registered under GST |
| Supplier GSTIN | Required | 15-character GSTIN of the seller |
| Invoice number | Required | Consecutive, unique per financial year |
| Invoice date | Required | Date of issue (must be ≤ date of supply) |
| Recipient name & address | Required | Buyer's details |
| Recipient GSTIN | B2B only | Mandatory for registered buyers (ITC claims) |
| Place of supply | Required | State name/code — determines IGST vs CGST+SGST |
| HSN / SAC code | Required | 4-digit (turnover ₹1.5–5Cr) or 6-digit (>₹5Cr) |
| Description of goods/services | Required | Clear description of what was sold |
| Quantity & unit | Goods only | For services, quantity is optional |
| Total value | Required | Gross value before deductions |
| Discount (if any) | If applicable | Post-supply discount reduces taxable value |
| Taxable value | Required | Value after discounts, on which GST is calculated |
| GST rate | Required | Rate applied per item (0/5/12/18/28%) |
| CGST + SGST or IGST amount | Required | Tax amount in ₹ for each component |
| Total invoice value | Required | Taxable value + all taxes |
| Digital/physical signature | Optional | Not mandatory under GST law; useful for disputes |
| # | Description | HSN | Qty | Rate | Taxable Value | GST 18% | Total |
|---|---|---|---|---|---|---|---|
| 1 | Office Chair – Ergonomic | 9401 | 2 | ₹5,000 | ₹10,000 | CGST ₹900 SGST ₹900 | ₹11,800 |
| 2 | Writing Desk – Wooden | 9403 | 1 | ₹8,000 | ₹8,000 | CGST ₹720 SGST ₹720 | ₹9,440 |
| Subtotal | ₹18,000 |
| CGST (9%) | ₹1,620 |
| SGST (9%) | ₹1,620 |
| Total | ₹21,240 |
The split depends on the place of supply compared to the supplier's location:
Example: Selling a ₹10,000 service at 18% GST from Mumbai to a Delhi client: 18% IGST = ₹1,800. Same sale to a Mumbai client: 9% CGST + 9% SGST = ₹900 + ₹900 = ₹1,800 total.
InvoiceKit handles all the calculations — CGST, SGST, IGST, discounts. Fill in details and download PDF in seconds.
Create Invoice Now →Supplier name, address and GSTIN; invoice number and date; recipient details and GSTIN (for B2B); place of supply; HSN/SAC code; description, quantity and rate; taxable value; GST rate and amount (CGST+SGST or IGST); and total invoice value.
CGST and SGST are charged on intra-state (within the same state) transactions — each at half the GST rate. IGST is charged on inter-state transactions at the full GST rate. Both result in the same total tax for the buyer, but the government distributes the revenue differently.
Yes. A consecutive, unique serial number is mandatory on every GST invoice. It can include letters, numbers, hyphens and slashes (max 16 characters) and must be unique within the financial year.
For sales above ₹200 to unregistered buyers, yes. For sales below ₹200 to unregistered buyers, you can issue a consolidated invoice for all such transactions during a day. For registered buyers (B2B), always issue an invoice regardless of amount.
HSN (Harmonised System of Nomenclature) is an international system for classifying goods. In India, businesses with annual turnover above ₹1.5 crore must mention HSN codes on invoices (4-digit for ₹1.5–5Cr, 6-digit for above ₹5Cr). You can find HSN codes on the GST portal (www.gst.gov.in) under the HSN Search tool.
Yes. You can create a GST invoice in Excel, Word, or using a free online tool like InvoiceKit. The law doesn't require special software — it only requires that all mandatory fields are present and the invoice is retained for 6 years. Free tools are fine for small businesses and freelancers.
Yes, under GST law the official document is called a "Tax Invoice." A GST invoice and tax invoice refer to the same document. Some states used to have separate VAT invoices before GST — those are now replaced by the unified GST tax invoice.