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GST Invoice Format: Every Rule 46 Field, Explained
Rule 46 of the CGST Rules is the checklist your buyer's accountant runs against your invoice — usually silently, and a failure usually surfaces as a delayed payment or a lost input credit conversation. Here is every field, what it means, and how it breaks.
The short version: a tax invoice must identify the supplier (name, address, GSTIN), itself (the words "Tax Invoice", a consecutive serial of at most 16 characters unique for the financial year, and the date), the recipient (name, address, GSTIN if registered, state name and code), the supply line by line (HSN/SAC, description, quantity with its unit, values before and after discount), the tax (rate per line, split as CGST+SGST intra-state or IGST inter-state), the place of supply, the reverse-charge position, and a signature. The generator checks this list live while you type.
The fields, one by one
| Field | Why it exists / how it breaks |
|---|---|
| Supplier name | Mandatory under Rule 46; its absence is a defect on the face of the document. |
| Supplier address | Mandatory under Rule 46; its absence is a defect on the face of the document. |
| Supplier GSTIN | Mandatory under Rule 46; its absence is a defect on the face of the document. |
| Document titled "Tax Invoice" | Mandatory under Rule 46; its absence is a defect on the face of the document. |
| Consecutive serial number (max 16 characters, unique for the financial year) | Consecutive and unique per financial year. Reused or gapped serials are the first thing an audit samples; per-type sequences (invoice, credit note) are kept separately. |
| Date of issue | Mandatory under Rule 46; its absence is a defect on the face of the document. |
| Recipient name | Mandatory under Rule 46; its absence is a defect on the face of the document. |
| Recipient address | Mandatory under Rule 46; its absence is a defect on the face of the document. |
| Recipient GSTIN (if registered) | Drives the B2B/B2C split in GSTR-1. A mistyped GSTIN with a bad checksum sends the buyer’s credit to the wrong place — which is why ours is checksum-validated and a failure excludes the invoice from the B2B export. |
| Recipient state name and code | Mandatory under Rule 46; its absence is a defect on the face of the document. |
| HSN code (goods) / SAC (services) on every line | HSN for goods, SAC for services. The invoice’s tax summary is grouped by code and rate; a missing code is the most common reason a "complete-looking" invoice is not complete. |
| Description of goods/services on every line | Mandatory under Rule 46; its absence is a defect on the face of the document. |
| Quantity and unit (UQC) on every line | Mandatory under Rule 46; its absence is a defect on the face of the document. |
| Total value of supply | Mandatory under Rule 46; its absence is a defect on the face of the document. |
| Taxable value (after discount) | Value after discount: the discount is applied to the line before tax. An unstated "discount after tax" habit quietly misstates every downstream figure. |
| Rate of tax on every line | Mandatory under Rule 46; its absence is a defect on the face of the document. |
| Tax amount split as CGST/SGST (intra-state) or IGST (inter-state) | Decided by the place of supply, not by preference: same state → CGST + SGST at half rate each; different state → IGST at the full rate. |
| Place of supply, with state name (inter-state supplies) | With the state name, for inter-state supplies. It is the input to the split above — get it wrong and both the tax head and the export section are wrong. |
| Whether tax is payable on reverse charge — stated on the document | Must be stated either way. Under reverse charge the recipient self-pays the tax, so the amount payable to the supplier excludes it. |
| Signature / digital signature of the supplier or authorised representative (placeholder block on the document) | Signature or digital signature of the supplier or authorised representative — rendered as a signature block on the document. |
Three failures that look like formatting but are not
1. The split follows the wrong state
The split follows the place of supply, not the buyer's billing address by default. Goods delivered in a third state, or services consumed elsewhere, change the answer. The generator pre-fills from the buyer's state and lets you override — and prints the rule it applied on the document.
2. Rounding done silently, twice
Section 170 rounds tax to the nearest rupee at the totals step. Tools that round every line and hide it produce invoices whose lines do not add up to their totals. Ours computes per line, rounds the component totals under section 170, keeps the taxable value exact to the paise (₹99.99 at 18% → tax ₹18, total ₹117.99), and states the policy here and in the method note.
3. A "complete" invoice with an invalid GSTIN
Every field filled, one checksum digit wrong. The invoice looks fine and fails in the return. The two-layer check — format, then checksum, worked by hand on the validator page — exists because of exactly this failure.