GST ACT SIMPLIFIED SERIES

A GST-compliant invoice is more than just a bill — it's the legal document that lets your buyer claim Input Tax Credit, and getting the format, contents, and timing right is a foundational GST compliance requirement for every registered business.

Mandatory Contents of a Tax Invoice

•      Name, address and GSTIN of the supplier

•      A consecutive serial number (unique for the financial year, up to 16 characters) and the date of issue

•      Name, address and GSTIN (or UIN) of the recipient, if registered; name, address of the recipient and address of delivery, along with the state name and code, if unregistered and the invoice value is ₹50,000 or more

•      HSN code (for goods) or SAC code (for services), as applicable based on turnover-linked digit requirements

•      Description, quantity (for goods) and unit of the goods/services supplied

•      Total value of supply, taxable value after adjusting for any discount, and the applicable GST rate

•      Amount of tax charged, broken down as CGST, SGST/UTGST, or IGST, as applicable

•      Place of supply, along with the name of the destination state, in the case of an inter-state supply

•      Whether tax is payable on reverse charge basis

•      Signature or digital signature of the supplier or an authorised representative (not required for electronically generated invoices in specified cases)

Time Limit for Issuing Invoices

•      Goods: before or at the time of removal of goods for supply to the recipient (where movement is involved), or at the time of delivery/making available to the recipient (where no movement is involved)

•      Services: within 30 days of the date of supply of service (extended to 45 days for banks, financial institutions, and NBFCs)

•      Continuous supply of goods/services: linked to successive statements of accounts or successive payments, as per the agreed contract terms

Other Common GST Document Types

•      Bill of Supply: issued instead of a tax invoice for exempt supplies, or by composition dealers, since no tax is separately charged on these

•      Debit Note: issued by the supplier when the taxable value or tax charged in an original invoice needs to be increased

•      Credit Note: issued by the supplier when the taxable value or tax charged needs to be reduced (e.g., for sales returns, post-sale discounts, or deficiency in service)

•      Receipt Voucher: issued on receipt of advance payment for a supply

•      Refund Voucher: issued when an advance received is subsequently refunded without the supply actually being made

•      Delivery Challan: used for movement of goods where a tax invoice cannot be issued at the time of removal, such as for job work, supply on approval basis, or transportation for reasons other than supply

E-Invoicing

E-invoicing is mandatory for businesses whose aggregate turnover in any preceding financial year (from FY 2017–18 onwards) exceeds a notified threshold — currently ₹5 crore, though this threshold has been progressively lowered over the years from an initial ₹500 crore when e-invoicing was first introduced.

Businesses covered by e-invoicing must generate their invoices through the government's Invoice Registration Portal (IRP), which validates the invoice data, generates a unique Invoice Reference Number (IRN), digitally signs it, and returns a QR code that must be printed on the physical or PDF copy of the invoice.

An invoice from a business covered under the e-invoicing mandate is not treated as a valid tax invoice for ITC purposes without a valid IRN — meaning the buyer's ITC claim can be jeopardised if the supplier fails to comply.

HSN and SAC Code Requirements on Invoices

•      Turnover up to ₹5 crore: 4-digit HSN code required on B2B tax invoices (optional for B2C)

•      Turnover above ₹5 crore: 6-digit HSN code required on all invoices

•      SAC codes for services generally follow a similar 6-digit structure and are mandatory in line with applicable notifications

Frequently Asked Questions

Q1. Is e-invoicing applicable to B2C (retail) sales too?

A. E-invoicing through the IRP is primarily for B2B supplies; for large B2C invoices, a separate dynamic QR code requirement may apply instead for very large taxpayers, depending on turnover and notification.

Q2. What is the current e-invoicing turnover threshold?

A. ₹5 crore aggregate turnover in any preceding financial year from 2017–18 onwards — this threshold has been progressively lowered from an initial ₹500 crore, so it's worth checking the latest CBIC notification for any further revision.

Q3. Can I edit an invoice after it has been registered on the IRP?

A. No, once an IRN is generated the invoice content cannot be edited on the IRP — it must be cancelled (generally within 24 hours of generation) and a fresh, corrected invoice issued if changes are needed.

Q4. What's the difference between a debit note and a credit note?

A. A debit note increases the value/tax of an original invoice (e.g., when an under-billing is corrected), while a credit note reduces it (e.g., for sales returns or discounts) — both must be reported in returns and affect the recipient's ITC correspondingly.

Q5. Is a signature mandatory on every GST invoice?

A. A physical or digital signature of the supplier or authorised representative is generally required, except for invoices issued in electronic form in accordance with the Information Technology Act, where specific rules for authentication apply.

Q6. What happens if my e-invoice-eligible business issues an invoice without generating an IRN?

A. The invoice may not be treated as a valid tax invoice, which can restrict the buyer's ability to claim ITC and may expose the supplier to penalties for non-compliance with the e-invoicing mandate.