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GST · Registration & returnsGST invoice rules: mandatory particulars and a sample checklist
A GST invoice that misses a mandatory field can cost your buyer their input tax credit – and you a customer. Here are the mandatory particulars under Rule 46, the time limits, special cases and a practical checklist.
Section 31 of the CGST Act requires a registered person to issue a tax invoice for taxable supplies, and Rule 46 of the CGST Rules prescribes its contents. An invoice is not just a bill – it is the document on which the buyer claims input tax credit.
Mandatory particulars (Rule 46)
- Name, address and GSTIN of the supplier.
- Consecutive serial number (max 16 characters, unique for the financial year; letters, numbers, "-" and "/").
- Date of issue.
- Name, address and GSTIN/UIN of the recipient (if registered).
- For unregistered recipients: name and address and State, where value is ₹50,000 or more (and for inter-State supplies, the State name).
- HSN code (goods) or SAC (services) – as per turnover rules.
- Description of goods or services.
- Quantity and unit (for goods).
- Total value.
- Taxable value after discounts.
- Rate of tax (CGST, SGST/UTGST, IGST, cess).
- Amount of tax for each.
- Place of supply with State name (for inter-State).
- Address of delivery, if different.
- Whether tax is payable on reverse charge.
- Signature or digital signature.
- QR code for B2C invoices of large taxpayers (turnover above ₹500 crore) and IRN/QR for e-invoices.
Time limits
| Supply | Invoice by |
|---|---|
| Goods involving movement | Before or at the time of removal |
| Goods without movement | Before or at the time of delivery / making available |
| Continuous supply of goods | Before or at the time of each statement/payment |
| Services | Within 30 days of supply (45 days for banks, insurers, NBFCs) |
| Continuous supply of services | By due date of payment / within 30 days of milestone |
Special documents
| Document | When |
|---|---|
| Bill of supply | Exempt supplies, or composition taxpayers |
| Receipt voucher | Advance received (services) |
| Refund voucher | Advance refunded without supply |
| Payment voucher / self-invoice | Reverse charge purchases from unregistered persons |
| Delivery challan | Movement without sale – job work, approval, exhibitions |
| Revised invoice | For the period between effective date of registration and issue of certificate |
Copies
- Goods: original for recipient, duplicate for transporter, triplicate for supplier.
- Services: original for recipient, duplicate for supplier.
- E-invoices: digital copy suffices.
Worked example: an invoice that fails
Example: Shree Ganesh Traders, Alipur, issues an invoice to a registered buyer in Haryana showing: supplier details, invoice number "SBE/45", date, buyer name and GSTIN, goods description, value ₹1,00,000, "CGST 9% ₹9,000 + SGST 9% ₹9,000".
Errors: - Inter-State supply → IGST 18% should be charged, not CGST+SGST. - Place of supply (Haryana) not mentioned. - HSN code missing (needed).
Consequences: buyer's GSTR-2B shows CGST+SGST from a Delhi supplier for a Haryana buyer – the buyer cannot use it properly; the supplier must pay IGST and seek a refund of CGST+SGST. A simple invoice template check would have prevented this.
Sample checklist before issuing
- [ ] Correct GSTIN of buyer (validate on the portal)
- [ ] Serial number continuous and unique
- [ ] HSN/SAC correct and with required digits
- [ ] Place of supply and tax type (IGST vs CGST+SGST) correct
- [ ] Rate as per current notification (post-September 2025 rates)
- [ ] Discounts shown before tax where applicable
- [ ] Reverse charge flag correct
- [ ] Signature / IRN and QR (if e-invoicing applies)
- [ ] E-way bill generated if goods move and value exceeds ₹50,000
Common mistakes
- Using different series without declaring them in Table 13 of GSTR-1.
- Invoices for services issued months later – late tax and interest.
- Missing buyer's State for unregistered inter-State supplies.
- Using old 12%/28% rates after the September 2025 rate changes.
Key takeaway
A compliant GST invoice protects both you and your buyer. Check the 17 particulars, time limits and tax type every time – ideally through your accounting software template. Our GST team reviews invoice formats and sets up templates in Tally, Busy and Zoho.
Official references
Provisions discussed (summaries in our Law Library):
- CGST Act, 2017 – Section 31: Tax invoice
- CGST Rules, 2017 – Section 46: Tax invoice particulars
Official sources to verify the current text, notifications and circulars:
Frequently asked questions
What is the time limit to issue a GST invoice for services?
Within 30 days from the date of supply of service (45 days for banks, insurers and NBFCs). For goods, at or before removal or delivery.
Is a signature mandatory on a GST invoice?
An invoice must be signed or digitally signed by the supplier or authorised representative. E-invoices authenticated with an IRN do not need a separate digital signature.
How many digits of HSN are required?
4 digits where aggregate turnover in the previous year was up to ₹5 crore, and 6 digits above ₹5 crore. For B2C invoices up to ₹5 crore turnover, HSN is optional on the invoice but required in GSTR-1.
Can I issue an invoice without the buyer's GSTIN?
For registered buyers, the GSTIN must be shown for them to claim ITC. For unregistered buyers, name and address are required where invoice value is ₹50,000 or more, or the place of supply is another State.
Can I issue invoices in a different series for each branch?
Yes. Multiple series are allowed, but each must be consecutive and unique within the financial year, and reported in the documents-issued table.
Is a handwritten invoice valid?
Yes, if it contains all prescribed particulars. Taxpayers covered by e-invoicing must generate IRNs for B2B invoices.
What if I cancel an invoice?
If goods were not supplied, cancel the invoice and report it as cancelled in Table 13; if supplied, issue a credit note instead.
This article is general information on the law as on 10 November 2026, written for educational purposes. It is not professional advice for your case. Section numbers under the Income-tax Act, 2025 should be confirmed with the official section mapping on the Income Tax Department website before use in filings.
Have a tax, GST or business question?
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