What Are the Contents of a Tax Invoice Under GST?

A GST tax invoice must carry the fields prescribed under Rule 46 of the CGST Rules, 2017: supplier and recipient identification, a unique serial number and date, a description of the goods or services with HSN or SAC codes, taxable value, tax rates and amounts split by head, place of supply for inter-state transactions, a reverse charge notation where applicable, and the supplier’s signature.¹ The contents of a tax invoice under GST matter for two reasons: the recipient cannot claim input tax credit without a valid invoice from a registered supplier,² and a missing field can trigger penalties of ₹10,000 or the full tax amount involved, whichever is higher, and up to ₹25,000 per invoice for procedural failures.³

Supplier and Recipient Details

Three pieces of supplier information open the invoice: the business name, registered address, and GSTIN. These let the recipient and the tax authorities verify that the supplier is registered and trace the transaction through the GST portal.¹

Two identifying fields follow. The serial number must be consecutive, unique to the financial year, and no longer than sixteen characters. It can combine letters, numbers, hyphens, and slashes, but no other special characters. The date of issue pins the invoice to a tax period and fixes when the supplier must report the transaction.

Recipient details depend on registration status. If the buyer is registered, the invoice must show their name, address, and GSTIN or Unique Identity Number. If the buyer is unregistered, the invoice needs the name, address, and delivery location (including state name and code) when the taxable value is ₹50,000 or more. Below that threshold, the supplier must still record these details if the unregistered recipient requests them.¹

Description, HSN Codes, and Value

Every line item needs a clear written description. For goods, the invoice must also show quantity and the applicable unit of measurement or Unique Quantity Code. The total value of the supply is the full amount before tax; the taxable value is the amount after any discount or abatement.¹

Rule 46 requires the Harmonised System of Nomenclature (HSN) code for goods and services. Services use a Services Accounting Code (SAC) that follows the same classification logic. The number of digits you must report depends on your aggregate turnover in the preceding financial year:

Turnover up to ₹5 crore: 2-digit HSN codes.
Turnover above ₹5 crore: 6-digit HSN codes.
Importers and exporters: 8-digit HSN codes regardless of turnover.

These thresholds were introduced through Notification No. 78/2020 and subsequent advisories.⁴ Wrong HSN codes are a frequent audit trigger.

Tax Breakdown and Place of Supply

The invoice must show the applicable tax rate and the tax amount for each line item, split across the relevant heads: Central Tax (CGST), State Tax (SGST), Integrated Tax (IGST), Union Territory Tax (UTGST), or cess. Which heads apply depends on whether the transaction is intra-state or inter-state.¹

For inter-state supplies, the invoice must state the place of supply along with the state name. That field determines whether IGST applies instead of the CGST-plus-SGST combination. If the delivery address differs from the place of supply, that address must also appear. An error here can send tax to the wrong state government, leaving you paying twice while the mismatch is sorted out.

Reverse Charge Notation and Signature

Rule 46(p) requires the invoice to state whether tax is payable on a reverse charge basis. Under reverse charge, the liability to pay GST shifts from the supplier to the recipient, so the invoice must make this clear. Omitting the notation can leave the recipient unaware that they must report and pay the tax in their own return.¹

The final mandatory field is the supplier’s signature, which can be physical or digital. For invoices generated electronically under the Information Technology Act, 2000, a digital signature satisfies the requirement.

Extra Endorsements for Exports and SEZ Supplies

Invoices for exports or supplies to Special Economic Zones carry every standard field plus one of two endorsement statements. If tax is being paid, the invoice must state that the supply is meant for export or supply to a SEZ unit or developer for authorised operations on payment of integrated tax. If the supply is under bond or letter of undertaking, the invoice must state that it is meant for export or supply to a SEZ unit or developer for authorised operations under bond or LUT without payment of integrated tax.¹

The invoice must also carry the recipient’s full name and address and the destination country. When the invoice is in a foreign currency, the equivalent INR value must appear alongside, converted at the applicable exchange rate on the date of supply.

When the Invoice Must Be Issued

Contents only matter if the invoice is issued on time. Section 31 of the CGST Act sets different deadlines by supply type:⁵

Goods involving movement: before or at the time of removal for delivery to the recipient.
Goods without movement: before or at the time of delivery, or when the goods are made available to the recipient.
Services: before or after providing the service, but within 30 days of the supply date.

Continuous supply arrangements follow their own timeline. For ongoing goods contracts with periodic payments or account statements, the invoice must go out before or at the time each statement is issued or payment is received. For continuous services, the trigger is the payment due date fixed in the contract, or the date of receipt of payment if no due date is fixed, or the completion of the linked event where payment is milestone-based.

E-Invoicing and the IRN Requirement

If your aggregate annual turnover has exceeded ₹5 crore in any financial year from 2017–18 onward, your B2B, B2G, and export invoices must be generated through the Invoice Registration Portal.⁶ You upload the invoice data, receive an Invoice Reference Number (IRN) and a digitally signed QR code, and embed both into the invoice before sending it to the recipient.

Rule 48(4) makes this mandatory for notified persons, and Rule 48(5) goes further: an invoice issued by a person covered by the e-invoicing requirement that does not follow this process is not treated as a valid invoice at all.⁷ The recipient cannot claim ITC against it, and the supplier remains exposed to penalties for not issuing a proper invoice.

The turnover threshold is calculated across all GST registrations under a single PAN, not state by state. If your business crosses ₹5 crore during a financial year, e-invoicing applies from the following financial year.

Copies of the Invoice

Rule 48 also prescribes how many copies you issue and how each is labelled.⁷ For goods, the invoice is prepared in triplicate: the original marked “Original for Recipient,” the duplicate marked “Duplicate for Transporter,” and the triplicate marked “Triplicate for Supplier.” For services, only two copies are needed, one for the recipient and one for the supplier’s records.

When a Bill of Supply Applies Instead

Not every registered person issues a tax invoice. Composition scheme dealers and suppliers making exempt supplies issue a bill of supply instead, governed by Rule 49. Its contents mirror most of the standard tax invoice fields, but with no tax breakdown because no GST is charged.⁸ A bill of supply carries no tax component, so the recipient cannot use it to claim input tax credit.

Revised Invoices, Credit Notes, and Debit Notes

Rule 53 governs the documents that adjust previously recorded transactions.⁹ A revised invoice must display the words “Revised Invoice” prominently and carry every identification field of a standard invoice, plus the serial number and date of the original tax invoice being corrected.

Credit notes reduce the original supply value for returns, post-sale discounts, or overcharges. Debit notes increase it for undercharges or additional amounts. Each must state its nature, carry its own serial number and date, reference every original invoice it modifies, and show the taxable value, applicable tax rate, and tax amount being adjusted.

Credit notes have a hard deadline. The supplier must declare a credit note in their return no later than 30 September following the end of the financial year of the original supply, or the date of filing the relevant annual return, whichever is earlier. Miss that window and the reduction in output tax liability is gone permanently.

Penalties and the Input Tax Credit Risk

Section 122 of the CGST Act creates two tiers of exposure. Supplying without an invoice, or with an incorrect or false invoice, attracts a penalty of ₹10,000 or the full tax amount involved, whichever is higher. Failing to issue an invoice in accordance with the Act or its rules, where there is no allegation of deliberate evasion, attracts a penalty of up to ₹25,000. Both apply per instance, so sloppy invoicing across many transactions compounds fast.³

The downstream cost is often worse. An improperly issued invoice jeopardises the recipient’s ITC claim under Section 16. If the invoice is not treated as valid, the recipient loses the right to offset the tax against their output liability, effectively paying it twice.²

How Long to Keep Invoice Records

Section 36 of the CGST Act requires you to retain all books of account and records, including copies of tax invoices, for at least 72 months from the due date of filing the annual return for the year the records relate to.¹⁰ That works out to roughly six years from the end of the relevant financial year. If you are involved in any appeal, revision, or investigation, the period extends to one year after final disposal of that proceeding, or the standard 72 months, whichever ends later.

1
Central Board of Indirect Taxes and Customs. CGST Rules – Rule 46 Tax Invoice
2
Central Board of Indirect Taxes and Customs. CGST Act – Section 16 Eligibility and Conditions for Taking Input Tax Credit
3
Central Board of Indirect Taxes and Customs. CGST Act – Section 122 Penalty for Certain Offences
4
Goods and Services Tax Network. Implementation of Mandatory Mentioning of HSN Codes in GSTR-1
5
Central Board of Indirect Taxes and Customs. CGST Act – Section 31 Tax Invoice
6
CGST Jaipur Commissionerate. E-Invoice Under GST
7
Central Board of Indirect Taxes and Customs. CGST Rules – Rule 48 Manner of Issuing Invoice
8
Central Board of Indirect Taxes and Customs. CGST Rules – Rule 49 Bill of Supply
9
Central Board of Indirect Taxes and Customs. CGST Rules – Rule 53 Revised Tax Invoice and Credit or Debit Notes
10
Central Board of Indirect Taxes and Customs. CGST Act – Section 36 Period of Retention of Accounts