Quick Answer
E-invoicing under GST means getting your B2B invoices registered on the government's Invoice Registration Portal (IRP) before issuing them. The system generates a unique Invoice Registration Number (IRN) and QR code for each invoice. Currently, businesses with an annual aggregate turnover (AATO) of Rs 5 crore and above must comply. The threshold is expected to drop to Rs 2 crore, meaning even smaller businesses will need to prepare. Non-compliance can result in penalties of up to Rs 25,000 per invoice.
What is E-Invoicing Under GST?
E-invoicing does not mean generating invoices online. You probably already do that with your billing software. E-invoicing is specifically about getting your invoices registered and validated by the government's system before you issue them to your buyer.
Here is how it works in simple terms:
- You create an invoice in your billing software as usual
- Your software sends the invoice data (in a specific JSON format) to the Invoice Registration Portal (IRP)
- The IRP validates the data, checks for errors, and assigns a unique Invoice Registration Number (IRN)
- The IRP also generates a QR code and digitally signs the invoice
- The validated invoice with IRN and QR code comes back to your software
- You issue this validated invoice to your buyer
The entire process takes a few seconds. From the user's perspective, if your billing software supports e-invoicing, it happens automatically in the background every time you create a B2B invoice.
Key Terms Explained
IRN (Invoice Registration Number): A 64-character unique number assigned to every e-invoice. Think of it as an Aadhaar number for your invoice. No two invoices in the country can have the same IRN.
IRP (Invoice Registration Portal): The government's portal that validates and registers invoices. The main portal is einvoice1.gst.gov.in. There are also private IRPs authorized by the government.
QR Code: Generated by the IRP for every e-invoice. Contains key invoice details (GSTIN, IRN, invoice value, etc.) and can be scanned for verification.
JSON Schema: The technical format in which invoice data is sent to the IRP. Your billing software handles this. You do not need to know the technical details.
Who Must Comply Right Now?
The e-invoicing mandate has been rolled out in phases, starting with large businesses and gradually expanding.
| Phase | Effective Date | Turnover Threshold | |-------|---------------|-------------------| | Phase 1 | October 2020 | Rs 500 crore and above | | Phase 2 | January 2021 | Rs 100 crore and above | | Phase 3 | April 2021 | Rs 50 crore and above | | Phase 4 | April 2022 | Rs 20 crore and above | | Phase 5 | October 2022 | Rs 10 crore and above | | Phase 6 | August 2023 | Rs 5 crore and above |
As of early 2026, the threshold stands at Rs 5 crore annual aggregate turnover (AATO). This means if your business had a turnover of Rs 5 crore or more in any financial year from 2017-18 onwards, you need to generate e-invoices for all B2B transactions.
Important: The threshold is based on aggregate turnover, which includes all supplies across all GSTINs under the same PAN. If you have multiple GST registrations in different states, the combined turnover is what counts.
The Proposed Rs 2 Crore Threshold
The government has been steadily lowering the threshold, and a reduction to Rs 2 crore has been discussed in multiple GST Council meetings. While the exact date has not been confirmed, the direction is clear: e-invoicing will eventually cover all GST-registered businesses.
What This Means for Small Businesses
If your annual turnover is between Rs 2 crore and Rs 5 crore, you should start preparing now rather than scrambling when the notification comes. Businesses that were caught off guard by previous threshold reductions faced weeks of disruption, rejected invoices, and delayed payments from buyers.
If your turnover is below Rs 2 crore, you likely have more time. But setting up your systems early means you are ready whenever the threshold reaches you.
Step by Step: How E-Invoice Generation Works
Step 1: Get Your Software Ready
Your billing or accounting software needs to support e-invoicing. This means it can generate invoice data in the required JSON format and communicate with the IRP through an API. Most major billing software in India (Tally, Zoho, Busy, ClearTax, and others) already support this. If you are using custom-built or very old software, check with your vendor.
Step 2: Register on the E-Invoice Portal
Visit einvoice1.gst.gov.in and register using your GSTIN. You will need to create API credentials (username and password) that your billing software uses to connect with the IRP.
Step 3: Configure Your Software
Enter your IRP API credentials in your billing software. Set up the integration so that invoices are automatically sent to the IRP when you create them. Your software vendor can help with this setup.
Step 4: Generate E-Invoices
From this point, the process is automatic. When you create a B2B invoice:
- Your software sends the data to the IRP
- The IRP validates it and returns the IRN, signed invoice, and QR code
- Your software embeds these into your invoice
- You print or share the invoice with IRN and QR code included
Step 5: Handle Cancellations
If you need to cancel an e-invoice, you must do it on the IRP within 24 hours of generation. After 24 hours, you cannot cancel the e-invoice. Instead, you need to issue a credit note (which itself needs to be registered as an e-invoice).
Common E-Invoice Errors and How to Avoid Them
Based on the most frequent issues businesses face after going live with e-invoicing:
Duplicate IRN Request
Error: "Duplicate IRN for the same document" Cause: You tried to generate an e-invoice for an invoice number that already has an IRN. Fix: Check if the invoice was already registered. If you need to re-issue, cancel the original within 24 hours or issue a credit note and a new invoice.
Invalid GSTIN
Error: "Recipient GSTIN is invalid or inactive" Cause: The buyer's GSTIN you entered is either wrong, deactivated, or cancelled. Fix: Verify the buyer's GSTIN on the GST portal before creating the invoice. Keep your customer master data updated.
HSN Code Mismatch
Error: "HSN code does not match the rate of tax" Cause: The HSN code you used does not correspond to the GST rate applied. Fix: Maintain a correct HSN code master in your software. Double-check when adding new products. The government has made 6-digit HSN codes mandatory for businesses above Rs 5 crore turnover.
Schema Validation Errors
Error: Various field-level validation errors Cause: Missing mandatory fields, wrong data formats, or values exceeding allowed length. Fix: Ensure your software is updated to the latest e-invoice schema version. Fields like pin code, state code, and supply type are commonly missed.
Timeout and Connectivity Issues
Error: "Unable to connect to IRP" or timeout errors Cause: The IRP servers can be slow during peak hours (end of month, return filing deadlines). Fix: Generate invoices during off-peak hours when possible. Have a retry mechanism in your software. Keep records of invoices pending IRN so you can retry later.
Penalties for Non-Compliance
Not generating e-invoices when required is a serious matter under GST law.
Penalty per invoice: The tax officer can impose a penalty of Rs 10,000 or the tax amount, whichever is higher, up to a maximum of Rs 25,000 per invoice. For a business issuing hundreds of invoices a month, this adds up to lakhs very quickly.
ITC impact on your buyer: If you do not generate an e-invoice, your buyer cannot claim Input Tax Credit (ITC) on that purchase. Large buyers (corporates, government departments) will refuse to accept non-e-invoiced bills. This means you could lose business even before any penalty hits.
GST return filing issues: The e-invoice data auto-populates your GSTR-1. Without e-invoices, your GSTR-1 will be incomplete, leading to notices and potential demand for tax with interest.
How to Prepare Even if Below the Current Threshold
Even if your turnover is below Rs 5 crore today, here is what you should do.
Audit Your Current Billing Setup
Can your current billing software generate e-invoices? If you are using printed bill books or basic Excel-based billing, you will need to upgrade. Check with your software vendor about e-invoicing support. If they do not support it, start evaluating alternatives now. See our GST billing software guide for what features to look for.
Clean Up Your Master Data
E-invoicing requires accurate data for every field. Common problem areas:
- Customer GSTINs: Verify every customer's GSTIN is active and correctly entered
- HSN codes: Make sure every product has the correct 4 or 6-digit HSN code
- State codes and pin codes: These are mandatory fields that many businesses leave blank in their current systems
- Your own business details: Legal name, trade name, and address must match your GST registration exactly
Do a Trial Run
Many billing software solutions let you generate e-invoices in sandbox (test) mode. The IRP also has a sandbox environment at einvoice1-sandbox.gst.gov.in. Run a batch of test invoices to see if your data passes validation.
Train Your Staff
The person who creates invoices in your business needs to understand what e-invoicing means, what the IRN is, when to cancel versus issue a credit note, and how to handle errors. A 30-minute training session can prevent weeks of confusion when you go live.
Plan for the Transition Period
When you start generating e-invoices, the first week will be slow. Errors will come up. Your team will need time to get comfortable. Plan this transition during a relatively quiet business period, not during your peak season.
E-Invoicing and GST Returns
One of the biggest advantages of e-invoicing is that it simplifies your GST return filing. Here is how:
Auto-population of GSTR-1: Your e-invoice data flows directly into your GSTR-1 return. You do not need to manually enter invoice details. This reduces data entry errors and saves hours of work.
Better ITC matching: Because both the seller's and buyer's invoices are registered on the same system, matching becomes automatic. Fewer mismatches mean fewer notices and blocked credits.
Reduced reconciliation work: The data in your books, your e-invoices, and your GST returns should all match. If they do not, you can identify and fix discrepancies much faster.
Frequently Asked Questions
Do I need to generate e-invoices for B2C (retail) sales?
No. E-invoicing currently applies only to B2B transactions, B2B exports, and supplies to SEZ units. If you sell directly to consumers (no GSTIN on the invoice), you do not need to generate e-invoices for those sales. However, your B2B transactions still need e-invoicing if your turnover exceeds the threshold.
My turnover was above Rs 5 crore two years ago but is below Rs 5 crore now. Do I still need to comply?
Yes. The threshold applies if your aggregate turnover exceeded the limit in any financial year from 2017-18 onwards. Even if your current turnover has dropped below the threshold, you must continue generating e-invoices. There is no opt-out once you cross the limit.
What happens if the IRP is down and I cannot generate an e-invoice?
You can generate the invoice in your software and issue it to the buyer. Then generate the e-invoice on the IRP once it is back online. However, do this as soon as possible. The government expects e-invoices to be generated in real-time or near real-time. Consistently generating invoices without IRN and adding them later can attract scrutiny.
Can I modify an e-invoice after it is generated?
No. Once an e-invoice is registered and an IRN is assigned, it cannot be modified. If you made an error, you have two options: cancel the e-invoice within 24 hours and create a new one, or issue a credit note (also registered as an e-invoice) and generate a corrected invoice.
How much does e-invoicing cost?
The government does not charge any fee for generating e-invoices on the IRP. The cost is primarily in your billing software (which may charge extra for the e-invoicing module) and the one-time setup effort. Many billing software providers include e-invoicing at no additional cost. Hardware costs are zero since you are using the same computer or device you already use for billing.