GST e-invoicing in India: who needs it and how it works

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GST e-invoicing in India requires businesses above a turnover threshold to report every B2B invoice to the government's Invoice Registration Portal, which returns a unique Invoice Reference Number and a signed QR code. An invoice that should have been registered but was not is not a valid tax invoice, which can cost your customer their input tax credit and cost you the sale. This guide explains who must comply, how the process works, how it links to GST returns and e-way bills, and how to choose software that handles it.

What GST e-invoicing means

E-invoicing under GST does not mean simply emailing a PDF invoice. It means that the invoice data is reported in a standard electronic format to an Invoice Registration Portal (IRP) operated for the GST Network. The IRP validates the data, generates a unique Invoice Reference Number (IRN), digitally signs the invoice and returns a QR code containing key details. The business then issues the invoice to the customer with the IRN and QR code.

The data flows automatically into the GST system, pre-filling the supplier's GSTR-1 and the buyer's input tax credit statement. This reduces fake invoicing and mismatches, and makes returns easier for both sides.

Who must use e-invoicing

E-invoicing is mandatory for GST-registered businesses whose aggregate annual turnover in any financial year since 2017-18 has exceeded ₹5 crore. Once a business crosses the threshold in any year, it must continue e-invoicing even if turnover later falls.

Some categories are exempt regardless of turnover, including certain banks and financial institutions, insurance companies, goods transport agencies, passenger transport services, multiplex cinema admissions, SEZ units and government departments. If you are near the threshold, check your aggregate turnover across all GSTINs under the same PAN, since the threshold applies to the PAN, not each registration.

Which documents are covered

E-invoicing applies to B2B supplies, exports and supplies to SEZs, and covers tax invoices, credit notes and debit notes. B2C invoices to consumers are not e-invoiced through the IRP, though businesses above a higher threshold must print a dynamic QR code on B2C invoices to enable digital payment. Delivery challans, bills of supply and some other documents are outside the scope.

The 30-day reporting rule

Businesses with aggregate turnover of ₹10 crore or more must report invoices to the IRP within 30 days of the invoice date. After 30 days, the IRP will not accept the invoice, which means it cannot be a valid e-invoice. The rule applies to invoices and credit and debit notes. Smaller e-invoicing businesses are not currently subject to this time limit, but reporting promptly is good practice for everyone.

The safest approach is to generate the IRN at the moment you raise the invoice, through software integrated with the IRP, so the 30-day rule never becomes an issue.

How the process works

1. Your billing or accounting software creates the invoice in the standard e-invoice schema (JSON).
2. The software sends it to an IRP through an API or a GST Suvidha Provider, or you upload it manually.
3. The IRP validates the data, checks for duplicates and generates the IRN.
4. The IRP digitally signs the invoice and returns it with a QR code.
5. You issue the invoice to the customer with the IRN and QR code printed.
6. Invoice details flow to GSTR-1 and, where applicable, the e-way bill system.

Within a short window after generation, currently 24 hours, an IRN can be cancelled entirely; after that, corrections must be made through credit or debit notes.

IRN and QR code explained

The Invoice Reference Number is a unique 64-character hash generated from the supplier's GSTIN, the financial year, document type and document number. Because it is based on the document number, you cannot register the same invoice number twice in a year.

The signed QR code contains the supplier and buyer GSTINs, invoice number and date, invoice value, number of items, the main HSN code and the IRN. Tax officers and customers can verify an invoice by scanning the code with the government's verification app. Make sure the QR code is printed clearly on every e-invoice.

E-invoicing and e-way bills

For movements of goods above the e-way bill value threshold, e-invoicing can generate the e-way bill at the same time. If you include transport details, such as the vehicle number or transporter ID, in the e-invoice request, the system can create the e-way bill automatically. This saves duplicate data entry for businesses that ship goods frequently. Make sure your software supports this combined flow if you move goods often.

E-invoicing and GST returns

Data from e-invoices auto-populates the relevant tables of GSTR-1, the monthly or quarterly return of outward supplies. Your customers see the invoices in their auto-generated input tax credit statements (GSTR-2B). This means that errors in e-invoices, such as a wrong customer GSTIN, flow through to your customer's credit. Review GSTR-1 before filing, and correct any mismatches through credit or debit notes rather than editing the return manually where possible.

GSTR-3B, the summary return with tax payment, is increasingly pre-filled from GSTR-1 and GSTR-2B, so accurate e-invoicing makes the whole cycle smoother.

GST rates after the 2025 reform

India simplified its GST rate structure in 2025. The main rates are now 5% for merit goods and services and 18% as the standard rate, with a special 40% rate for certain luxury and sin goods, plus nil-rated and exempt supplies. Your software's item master must use the correct HSN or SAC code and rate for each product or service, because e-invoices carry item-level tax details. Our GST calculator helps with quick calculations.

Choosing software

You have three main routes to e-invoicing:

• Accounting or billing software with built-in IRP integration, which generates IRNs automatically as you invoice. Best for most small and mid-sized businesses.
• ERP integration through a GST Suvidha Provider, common for larger businesses with their own systems.
• Manual generation on the IRP portal or the offline tool, suitable only for very low volumes.

Compare Indian accounting software in our India accounting software ranking and India accounting software guide, and see Zoho Books pricing in India and Busy pricing.

Features to check

• Automatic IRN generation when an invoice is saved.
• Bulk generation for high volumes.
• Credit and debit note support.
• E-way bill generation from the same data.
• GSTIN validation for customers.
• Correct HSN and SAC codes in the item master.
• GSTR-1 export and reconciliation with the portal.
• Multi-GSTIN support for businesses with several registrations.
• Audit trail and user permissions.

Setting up e-invoicing

1. Confirm that your aggregate turnover requires e-invoicing.
2. Register on the e-invoice portal using your GST credentials.
3. Choose software and enable API access, or set up a GSP connection.
4. Clean your customer master: correct GSTINs, addresses and state codes.
5. Update your item master with HSN/SAC codes and current rates.
6. Test with a few invoices and check the QR codes.
7. Train staff who raise invoices and credit notes.

Penalties for non-compliance

Issuing an invoice without an IRN when e-invoicing is required can lead to penalties under the GST law, and the invoice may not be treated as valid. That can block your customer's input tax credit, which damages relationships with business customers who rely on it. E-way bill rules also apply to goods in transit, and missing documents can lead to detention of goods. The simplest protection is software that will not let you issue a B2B invoice without generating an IRN.

Payments and collections

E-invoicing does not change how you get paid, but clean invoices with correct details reduce disputes and speed up payment. For online collections, see how to accept online payments in India and the India payment gateways ranking, and estimate costs with the payment fee calculator. For selling abroad, see how to invoice international clients.

Common mistakes

• Not tracking aggregate turnover across all GSTINs under one PAN.
• Issuing B2B invoices without an IRN after crossing the threshold.
• Missing the 30-day reporting window for businesses at ₹10 crore and above.
• Wrong customer GSTINs or state codes.
• Outdated HSN codes or rates after the 2025 rate changes.
• Editing invoices after IRN generation instead of issuing credit notes.

Example: a manufacturer crossing the threshold

A small manufacturer in Pune had aggregate turnover of ₹4.6 crore last year and ₹5.3 crore this year. As soon as the year's turnover crossed ₹5 crore, e-invoicing became mandatory from the date set in the rules, and it remains mandatory even if turnover falls back. The business updated its billing software to generate IRNs, cleaned its customer list, which had several outdated GSTINs, and added transport details to invoices so e-way bills were created automatically.

The first month showed a few rejections, mostly for customer GSTINs that had been cancelled and invoice numbers reused across branches. After fixing the numbering series by branch and validating GSTINs at the time of order, rejections dropped to near zero. The lesson: most e-invoicing problems are master data problems, not technical ones.

Invoice numbering and series

Because the IRN is generated from the GSTIN, financial year, document type and number, every document number must be unique within a financial year for each GSTIN. Businesses with several branches, counters or systems should use separate series with clear prefixes, such as a branch code, and reset numbering only at the start of a financial year. Credit notes and debit notes need their own series. Plan this before going live, because changing numbering later can create duplicates that the IRP rejects.

Handling exports and SEZ supplies

Exports and supplies to SEZ units must also be e-invoiced. For exports, the buyer details show the foreign recipient and a special code for the country instead of a GSTIN, and the invoice must indicate whether the export is with or without payment of IGST. Shipping bill and port details can be added later. If you export services, the same applies for invoices to overseas clients. For getting paid internationally, see how to get paid by international clients.

Credit notes and corrections

After the cancellation window, you cannot amend an e-invoice. Errors in value, quantity or tax must be corrected with a credit note or debit note, which is itself e-invoiced with its own IRN and references the original invoice. Errors in non-financial details, such as an address, may be corrected in GSTR-1 within limits, but the e-invoice record remains. Train staff to check invoices carefully before saving, since prevention is easier than correction.

Monitoring and reconciliation

Set up a monthly routine: compare invoices in your books with e-invoices registered on the portal, check that every B2B invoice has an IRN, review rejections and their reasons, and reconcile GSTR-1 with your sales register before filing. Also reconcile purchase invoices with GSTR-2B so that your own input tax credit is complete. Many accounting tools include reconciliation reports that make this quick.

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