Last updated: 6 October 2026. A GST tax invoice for goods must be issued before or at the time the goods are removed or delivered (Section 31(1) of the CGST Act). For services, it is due within 30 days of the supply, or 45 days for banks, insurers and NBFCs (Rule 47). Rule 46 of the CGST Rules lists what the invoice has to show. A handful of those details decide whether your buyer can claim input tax credit on it.
Applicability Note: This guide is based on GST provisions applicable as of 6 October 2026, read from CBIC's active repository that day. Always verify the current position on gst.gov.in or with a GST professional before taking action.
Who Should Care?
This guide applies to:
- Shopkeepers and traders billing more customers than usual during festive sales
- Freelancers and service providers who invoice after the work is done
- Composition taxpayers and sellers of exempt goods who issue a bill of supply instead
- Businesses that buy from unregistered suppliers and pay tax under reverse charge
1. Which Document Section 31 Asks You to Issue
"Invoice" in GST covers several documents. Section 31 tells you which one fits your situation:
| Situation | Document | Provision |
|---|---|---|
| Taxable supply of goods or services | Tax invoice | Section 31(1), 31(2); Rule 46 |
| Exempt supplies, or you pay tax under the composition scheme | Bill of supply | Section 31(3)(c); Rule 49 |
| Taxable and exempt supplies together, to an unregistered buyer | One "invoice-cum-bill of supply" | Rule 46A |
| Advance received before supply | Receipt voucher | Section 31(3)(d) |
| Advance received, but no supply and no invoice follow | Refund voucher (optional) | Section 31(3)(e) |
| You pay tax under reverse charge on a purchase from an unregistered supplier | Self-invoice, plus a payment voucher when you pay | Section 31(3)(f), (g); Rule 47A |
| Supplies made between your registration's effective date and the date the certificate was issued | Revised invoice | Section 31(3)(a); Rule 53 |
The credit and debit notes you issue after an invoice are covered by Section 34 and Rule 53(1A). We have a separate guide to those.
2. What Rule 46 Says a Tax Invoice Must Show
Rule 46 lists its particulars as clauses (a) to (s). Some apply to every invoice and some only in certain cases:
| Applies to | Particulars | Rule 46 clause |
|---|---|---|
| Every invoice | Your name, address and GSTIN | (a) |
| Every invoice | A consecutive serial number of up to 16 characters (letters, numbers, hyphen and slash only), unique for the financial year | (b) |
| Every invoice | Date of issue | (c) |
| Registered buyer | Buyer's name, address and GSTIN (or UIN) | (d) |
| Unregistered buyer, taxable value ₹50,000 or more | Buyer's name and address, delivery address, and the State name and code | (e) |
| Unregistered buyer, below ₹50,000 | The same details, only if the buyer asks for them | (f) |
| Every invoice | HSN code (see Section 3 for how many digits), description, and for goods the quantity and unit | (g), (h), (i) |
| Every invoice | Total value, and taxable value after any discount or abatement | (j), (k) |
| Every invoice | Rate and amount of tax, shown separately for CGST, SGST/UTGST, IGST and cess | (l), (m) |
| Inter-State supply | Place of supply, with the State name | (n) |
| Delivery elsewhere | Delivery address, where it differs from the place of supply | (o) |
| Every invoice | Whether tax is payable on reverse charge | (p) |
| Every invoice | Signature or digital signature of you or your authorised representative | (q) |
| E-invoices | QR code carrying the Invoice Reference Number (IRN) | (r) |
| Above the e-invoice threshold but exempt from it | A declaration that you are not required to e-invoice | (s) |
Rule 46 is subject to Rule 54, which relaxes the particulars for banks, insurers and NBFCs, goods transport agencies and passenger transport. Everyone else follows the table above.
An electronic invoice issued under the Information Technology Act, 2000 doesn't need a signature. That proviso was inserted by Notification No. 74/2018-Central Tax dated 31 December 2018.
On numbering, Rule 46(b) allows "one or multiple series" and only asks that each number be unique within the financial year. Most businesses start a fresh series on 1 April, and it's a sensible habit, but the rule doesn't require it.
Export and SEZ invoices need an endorsement: "SUPPLY MEANT FOR EXPORT/SUPPLY TO SEZ UNIT OR SEZ DEVELOPER FOR AUTHORISED OPERATIONS ON PAYMENT OF INTEGRATED TAX", or the "UNDER BOND OR LETTER OF UNDERTAKING WITHOUT PAYMENT OF INTEGRATED TAX" version. In place of clause (e), they also show the recipient's name and address, the delivery address and the country of destination.
3. How Many HSN Digits Go on the Invoice
The digit rule sits in Notification No. 12/2017-Central Tax dated 28 June 2017, as amended by Notification No. 78/2020-Central Tax dated 15 October 2020, which has applied since 1 April 2021. The test is your aggregate turnover in the preceding financial year:
| Aggregate turnover, preceding financial year | HSN digits on the tax invoice |
|---|---|
| Up to ₹5 crore | 4 digits. May be left out on invoices to unregistered persons |
| More than ₹5 crore | 6 digits |
One class cuts across both brackets. Notification No. 90/2020-Central Tax dated 1 December 2020 requires 8-digit HSN on the tax invoice for 49 specified chemicals, whatever your turnover.
This is the rule for the invoice itself. How HSN is reported in Table 12 of GSTR-1 is a separate question, covered in our HSN reporting guide. The ₹5 crore figure here is also not the e-invoicing threshold covered in section 6 below, which uses a different test.
4. When the Invoice Is Due
| Supply | Invoice due | Provision |
|---|---|---|
| Goods that move | Before or at the time of removal | Section 31(1)(a) |
| Goods that don't move | Before or at delivery or making available | Section 31(1)(b) |
| Services | Within 30 days of the date of supply | Section 31(2); Rule 47 |
| Services by an insurer, banking company or financial institution (including an NBFC) | Within 45 days | First proviso to Rule 47 |
| Continuous supply of goods | Before or at each statement of account or each payment | Section 31(4) |
| Continuous supply of services | On or before the due date of payment if the contract fixes one; otherwise when payment is received; for event-linked payments, on or before the event | Section 31(5) |
| Goods sent on approval or sale-or-return | At supply or six months from removal, whichever is earlier | Section 31(7) |
| Self-invoice under reverse charge (unregistered supplier) | Within 30 days of receiving the goods or services | Section 31(3)(f); Rule 47A |
Worked example
A designer finishes a festive campaign for a retailer on 3 October 2026. The invoice is due within 30 days of that supply, so 2 November 2026 is the last day. Suppose the same retailer receives a supply from an unregistered supplier on 7 October 2026 on which it has to pay tax under reverse charge. It must self-invoice within 30 days of receipt, so by 6 November 2026, and issue a payment voucher when it pays.
Rule 47A has applied since 1 November 2024. It was inserted by Notification No. 20/2024-Central Tax dated 8 October 2024, alongside the words "within the period as may be prescribed" added to Section 31(3)(f) by the Finance (No. 2) Act, 2024. The same notification removed an older Rule 46 proviso that had allowed one consolidated monthly invoice for Section 9(4) purchases above ₹5,000 a day. Since 1 November 2024, a supplier registered only to deduct TDS under Section 51 also counts as "not registered" for this purpose. Our reverse charge guide explains when RCM applies.
5. Special Cases: Under ₹200, Revised Invoices and Copies
Sales under ₹200
Under Section 31(3)(b) and a proviso to Rule 46, you may skip the individual invoice when the value is under ₹200, but only if the buyer is unregistered and doesn't want one. You must then issue one consolidated tax invoice at the close of each day for all such sales. Multiplex cinema admission is excluded. A bill of supply has the same under-₹200 relief under the proviso to Section 31(3)(c).
Revised invoices after registration
Registration is sometimes granted from a date earlier than the date the certificate is issued. In that case, Section 31(3)(a) lets you issue revised invoices for supplies made in the gap, within one month of the certificate. Rule 53(1) requires the words "Revised Invoice" and the number and date of the original invoice. For unregistered buyers you may issue one consolidated revised invoice. For inter-State supplies to unregistered buyers, where the value of a supply does not exceed ₹2,50,000, the consolidated revised invoice can be issued separately for each State.
How many copies
Under Rule 48, a paper invoice for goods is made in triplicate: original for recipient, duplicate for transporter, triplicate for supplier. For services it is made in duplicate. These copy rules do not apply to e-invoices.
6. If You Are on E-Invoicing
E-invoicing applies to registered persons whose aggregate turnover in any financial year from 2017-18 onwards exceeds ₹5 crore. The figure was cut from ₹10 crore by Notification No. 10/2023-Central Tax dated 10 May 2023, effective 1 August 2023, and some categories of business are exempt. If you are covered, Rule 48(5) is blunt: an invoice issued without an IRN from the portal "shall not be treated as an invoice". Our e-invoicing guide covers the process. If you have crossed ₹5 crore but are in an exempt category, Rule 46(s) asks you to put a declaration on your invoices saying so.
7. What a Missing Detail Can Cost
Your buyer's input tax credit
Rule 36(2) says ITC may be taken only if the document carries all the applicable particulars. Its proviso softens that. Credit may still be availed if the invoice shows:
- the amount of tax charged
- a description of the goods or services
- the total value of supply
- the GSTIN of both supplier and recipient
- for an inter-State supply, the place of supply
A missing field outside that list is not, by itself, a Rule 36(2) bar. Getting one of these wrong is. A wrong buyer GSTIN is a common one. The invoice also has to appear in the supplier's GSTR-1 or IFF and reach the buyer's GSTR-2B (Rule 36(4)), along with the other Section 16 conditions. A complete invoice is necessary for credit. It is not enough on its own.
There is one case where a missing detail takes the whole invoice down. If an e-invoice-mandated supplier issues an invoice without an IRN, Rule 48(5) says it is not an invoice at all, and the buyer has nothing to claim against.
Your own penalty exposure
Two provisions can apply. Section 122(1)(i) covers supplying "without issue of any invoice" or issuing "an incorrect or false invoice". The penalty is ₹10,000 or the tax evaded, whichever is higher, so ₹10,000 is the minimum, under each of the CGST and State GST Acts. Section 122(3)(e) separately covers a person who "fails to issue invoice in accordance with the provisions of this Act or the rules made thereunder", with a penalty that may extend to ₹25,000. That is a ceiling, not a floor. The Act does not define "incorrect", so which provision an officer invokes for an invoice with a missing field depends on the facts. Section 126 also limits penalties for minor breaches and easily rectifiable mistakes made without fraud or gross negligence. Our Section 122 guide explains how these work.
8. A Festive-Season Invoice Check
Rule 48(3) requires the serial numbers of invoices issued in a tax period to be reported in GSTR-1. Monthly filers report September invoices in the GSTR-1 due Sunday, 11 October 2026. QRMP filers report July to September in the quarterly GSTR-1 due Tuesday, 13 October 2026. That is also the due date for GSTR-5 and GSTR-6 (see our October 2026 calendar). Due dates are subject to notification changes, so verify on the GST portal before filing. Before then:
- Check every B2B invoice for the buyer's GSTIN. It is the field most likely to cost them credit.
- Look for gaps or repeats in each invoice series, especially if extra counters or billing devices were added for the season.
- Confirm that the HSN digits match your turnover bracket.
- Make sure the day's under-₹200 cash sales have their consolidated invoice.
- Diarise the 30-day limit for service invoices and reverse charge self-invoices.
Key Takeaways
- Goods need the invoice before or at removal or delivery. Services need it within 30 days of supply, or 45 days for banks, insurers and NBFCs.
- Exempt suppliers and composition taxpayers issue a bill of supply under Rule 49, not a tax invoice.
- HSN on the invoice: 4 digits up to ₹5 crore aggregate turnover in the preceding year, 6 digits above, under Notification No. 78/2020-Central Tax; 8 digits for 49 specified chemicals under Notification No. 90/2020-Central Tax, whatever the turnover.
- Reverse charge self-invoices for purchases from unregistered suppliers are due within 30 days of receipt under Rule 47A.
- Under the Rule 36(2) proviso, the buyer's credit turns on tax amount, description, total value, both GSTINs and, for inter-State supplies, place of supply.
- Invoice numbers must be unique within the financial year. Resetting the series on 1 April is good practice, not a legal requirement.
Frequently Asked Questions
What is the time limit to issue a GST invoice for services?
30 days from the date of supply of the service under Rule 47 of the CGST Rules. Insurers, banking companies and financial institutions including NBFCs get 45 days.
Is a GST invoice required for sales below ₹200?
Not individually, if the buyer is unregistered and doesn't ask for one (Section 31(3)(b)). You must still issue a consolidated tax invoice at the end of each day for all such sales.
Can my buyer claim ITC if my invoice is missing a detail?
Often yes. Under the proviso to Rule 36(2), the buyer can still claim credit if the invoice shows the tax amount, description, total value, both GSTINs and, for inter-State supplies, the place of supply, and the other Section 16 conditions are met. An invoice from an e-invoice-mandated supplier without an IRN is not an invoice at all under Rule 48(5).
When must I raise a self-invoice under reverse charge?
Within 30 days of receiving goods or services from an unregistered supplier, under Rule 47A, inserted by Notification No. 20/2024-Central Tax dated 8 October 2024 and effective from 1 November 2024.
Do I have to restart invoice numbering every financial year?
No. Rule 46(b) only requires each number to be unique within the financial year, and allows multiple series. Starting a new series on 1 April is the usual way to guarantee that.
⚠️ For informational purposes only.
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