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A small-business owner wants to know what a GST tax invoice must show and why buyers keep asking for corrections.
Rule 46 lists mandatory particulars: supplier and buyer GSTIN, a unique number up to 16 characters, date, HSN or SAC, taxable value, rate and tax split, place of supply and signature. Each is a key the buyer matches in GSTR-2B.
An invoice template with every Rule 46 field, a GSTIN check on the customer master, and place of supply set from the delivery state.
Invoices that the buyer can match first time, with the right tax split and no lost ITC.
A tax invoice is the document a registered supplier issues when making a taxable sale. Rule 46 of the CGST Rules lists what it must contain: your details and GSTIN, the buyer’s details and GSTIN, a unique number and date, the HSN or SAC code, the taxable value, the GST rate and amount split into CGST and SGST or IGST, the place of supply for inter-state sales, and a signature.
Each field also matters to your buyer. They match your invoice against their GSTR-2B line by line, and a wrong value costs them input tax credit (ITC).
The mandatory fields, and what goes wrong if one is wrong
| Field | Why it matters | What breaks if wrong |
|---|---|---|
| Supplier name, address, GSTIN | Identifies who charged the tax | Invoice cannot be traced to your return |
| Buyer name, address, GSTIN (15 characters) | Routes the invoice to the buyer’s GSTR-2B | Invoice lands in another business’s GSTR-2B; real buyer loses ITC |
| Invoice number (up to 16 characters, unique for the year) | Matching key | Duplicate or mistyped number fails the match |
| Invoice date | Decides the tax period | Invoice shows in a different month’s GSTR-2B |
| HSN or SAC code and description | Decides the rate | Wrong rate, wrong HSN summary |
| Quantity and unit | Physical check | Goods receipt and invoice disagree |
| Taxable value | Base for tax | Value mismatch in reconciliation |
| GST rate and amount, CGST/SGST or IGST | Tax payable and credit | Wrong head means credit under the wrong ledger |
| Place of supply (inter-state) | Decides IGST against CGST plus SGST | Tax paid under the wrong head |
| Signature or digital signature | Authenticity | Document can be questioned |
The “reverse charge applies” statement, delivery address (if different) and IRN with QR code are added where relevant.
When does a tax invoice also need an IRN and a QR code?
If your aggregate turnover crossed ₹5 crore in any year from 2017-18, your B2B invoices must be registered on the Invoice Registration Portal, which returns a 64-character IRN and a signed QR code. See what an e-invoice is.
What changes when the buyer is in another state?
The tax head changes. A sale within your state carries CGST plus SGST, half each. A sale to another state carries IGST at the full rate. The total tax is the same. What decides it is the place of supply, which is normally where the goods are delivered.
Worked example: the same ₹1,18,000 sale, two buyers
A Chennai manufacturer sells goods with a taxable value of ₹1,00,000 at 18 percent GST.
| Detail | Buyer in Chennai | Buyer in Bengaluru |
|---|---|---|
| Taxable value | ₹1,00,000 | ₹1,00,000 |
| CGST at 9 percent | ₹9,000 | Nil |
| SGST at 9 percent | ₹9,000 | Nil |
| IGST at 18 percent | Nil | ₹18,000 |
| Invoice total | ₹1,18,000 | ₹1,18,000 |
| Place of supply | Tamil Nadu | Karnataka |
If the Bengaluru invoice wrongly shows CGST and SGST, the supplier has paid tax under the wrong head and the buyer’s credit appears as CGST and SGST instead of IGST. Fixing it means a credit note and a fresh invoice.
Key rules to remember
- Businesses with turnover of ₹10 crore or more must register each invoice on the IRP within 30 days of its date (since 1 April 2025).
- The buyer must claim ITC by 30 November following the financial year under Section 16(4).
- A wrong invoice already reported is corrected by a credit note under Section 34 or a debit note, not by editing.
What to read next
- Next in this series: Tax invoice vs bill of supply: which one do you issue?
- How the buyer matches these fields: GSTR-2B vs purchase register reconciliation
- IRN records against the books: E-invoice reconciliation in India
- GST reconciliation software: GST outward reconciliation (GSTR-1 and GSTR-3B) leads the TransactIG GST roadmap; inward matching is on the roadmap.