E Invoicing Under GST: A Simplified Guide

E invoicing under GST is now mandatory for certain businesses, but the rules, turnover limits, and compliance process can get overwhelming. 

Let us help you understand GST E invoicing eligibility, rules, step by step process, benefits, and more in this simplified guide. 

What is E Invoicing Under GST?

E-invoicing under GST (Goods and Services Tax) is a system that requires certain businesses to authenticate and validate their invoices electronically. 

It is to be done in a government-specified format using a government-authorized platform called the Invoice Registration Portal (IRP). 

Every eligible invoice is validated, digitally signed, and assigned a unique Invoice Reference Number (IRN) and QR code.

IMPORTANT: E-Invoicing Is NOT Invoice Creation

E-invoicing doesn’t mean businesses must generate invoices on a government website.

Instead, it means submitting already-prepared invoice details, created through your own ERP or accounting software, in a structured format (JSON) to the IRP for validation and authentication.

Once validated, the invoice becomes a legally recognized e-invoice, ready for use in GST return filing, e-way bill generation, and input tax credit (ITC) reconciliation.

E Invoicing Applicability Under GST

E-invoicing under GST applies only to specific businesses based on their annual aggregate turnover (AATO) and nature of transactions. 

Let’s take a look at its applicability, eligibility, threshold and more:

Turnover Threshold for E-Invoicing Applicability

E-invoicing is mandatory for GST-registered businesses whose aggregate annual turnover exceeds a specified limit in any financial year from 2017–18 onwards.

Financial Year	Turnover Threshold	Effective From
2020–21	₹500 crore and above	1st October 2020
2021–22	₹100 crore and above	1st January 2021
2022–23	₹20 crore and above	1st April 2022
2023–24	₹10 crore and above	1st October 2022
2023–24 (latest)	₹5 crore and above	1st August 2023

Currently, E-invoicing is mandatory for businesses with aggregate turnover exceeding ₹5 crore in any financial year since 2017–18.

How Is Aggregate Turnover Calculated?

• Turnover includes taxable, exempt, export, and inter-state supplies.
• It is calculated PAN-wise, summing up the turnover of all GSTINs under a single PAN across India.
• GST and cess amounts are excluded from turnover calculation.

Who Must Comply With E-Invoicing: Transactions & Documents Covered

If your business meets the turnover threshold, e-invoicing is mandatory for specified transactions and documents.

Transactions Covered Under E-Invoicing : 

• B2B (Business-to-Business) Transactions: GST registered business supplies goods or services to another registered business.
• Exports: All export transactions (goods and services), with or without payment of IGST (zero rated supply under GST) 
• B2G (Business-to-Government) Transactions: Supplies made to government departments or agencies that are registered under GST.
• SEZ Developer Transactions: Supplies made to SEZ developers (not SEZ units).
• Deemed Exports: Supplies notified as deemed exports under GST (e.g., supplies to EOU units).
• Reverse Charge Mechanism (RCM) Transactions: When a supplier makes supplies that fall under RCM, and the recipient is liable to pay GST

Documents Covered Under E-Invoicing

• Tax Invoices for B2B, B2G, export, and SEZ transactions. Must be reported to the IRP for validation and generation of the Invoice Reference Number (IRN) and QR code.
• Credit Notes issued when the value of the original invoice is reduced: Must reference the original invoice already registered with the IRP.
• Debit Notes issued when the invoice value increases: Also needs to be linked to the original tax invoice.

Only three specific document types are accepted by the Invoice Registration Portal (IRP) for e-invoicing purposes in the prescribed JSON format.

Who is Exempt From E-Invoicing: Transactions and Documents NOT Covered

Some sectors and entities are exempt from e-invoicing, even if they exceed the turnover threshold. These include:

• Banks and Financial Institutions
• Insurance Companies
• Non-Banking Financial Companies (NBFCs)
• Goods Transport Agencies (GTAs)
• Passenger Transport Services
• Multiplexes showing cinematographic films
• Special Economic Zone (SEZ) units (but not SEZ developers)
• Government Departments and Local Authorities (unless registered under GST)

Apart from these sectors, the following are outside the scope of e-invoicing, even if issued by a business that crosses the turnover threshold:

• B2C (Business-to-Consumer) Transactions: Sales made to unregistered persons (end consumers). Though businesses with turnover > ₹500 crore must include dynamic QR codes on B2C invoices
• Bills of Supply: Used for exempt or non-taxable supplies, such as services by banks or education services.
• Delivery Challans: Issued for movement of goods without a sale (e.g., job work, testing, approval basis).
• Imports: Inbound transactions, such as import of goods or services
• Financial or Commercial Credit Notes: Not issued under Section 34 of the CGST Act and hence not covered.
• Supplies by Exempt Entities: Entities exempt from e-invoicing do not need to generate IRNs for any of their transactions:

How to Check If E-Invoicing Applies to Your Business

You can verify e-invoicing applicability through the official government portal:

Use the “Search by GSTIN” feature to check if your business is required to comply.

E Invoicing Reporting Timeline 

As per the latest update in effective April 1, 2025:

• Businesses with turnover ₹10 crore or more will be required to report invoices to the IRP within 30 days of invoice issuance.
• This change introduces a reporting deadline to enhance real-time compliance.

Process of Generating an E Invoice Under GST 

Before you start, here’s a quick checklist: 

Requirement	Description
GST Registration	Business must be registered under GST
Applicable Turnover Threshold	Meet the AATO limit (₹5 Cr as per latest rule)
ERP/Billing Software	Capable of exporting invoices in JSON format as per GSTN schema
IRP Access	Can access the Invoice Registration Portal

Here’s a look at the step by step process to Generate an e-Invoice under GST:

Step 1: Invoice Creation in Your Software

• Create the invoice using your billing, accounting or ERP system (e.g., Tally, SAP, Zoho, Busy, Marg, QuickBooks).
• Invoice must include:
  • Supplier and Recipient GSTIN
  • Invoice number & date
  • Item description with HSN codes
  • Taxable value, CGST/SGST/IGST
  • Invoice type (B2B, Export, SEZ, etc.)

Step 2: Convert Invoice to JSON Format

• The software should be capable of producing invoice data in JSON format as per the prescribed e invoice schema.
• This file structure is machine-readable and mandatory for uploading to the IRP.

Step 3: Upload JSON to Invoice Registration Portal (IRP)

You can upload invoice JSON to IRP using any of the following methods:

Upload Method	Best For
API Integration	Mid-to-large businesses using ERP systems
GSP (GST Suvidha Provider)	Third-party apps handling GST compliance
Offline Tool	Small businesses uploading manually
Web Portal Upload	Occasional or low-volume invoice generators.

Step 4: Validation by IRP

IRP performs:

• De-duplication check: Same invoice number + GSTIN + FY
• Schema validation: All required fields must be correctly filled
• GSTIN checks: Verifies supplier and buyer GSTINs are valid and active

✅ If successful:

• IRP generates a 64-character IRN (Invoice Reference Number).
• IRP digitally signs the invoice.
• A QR code is generated with key invoice details:
  • IRN
  • GSTINs
  • Invoice number & date
  • Tax amount & total value

⚠️If validation fails:

• IRP returns an error code and message (e.g., duplicate invoice, invalid GSTIN).
• You must correct and re-upload the invoice JSON.

You cannot issue a valid invoice until the IRN is generated.

Step 5: Signed Data Returned to Supplier

• IRP sends back digitally signed JSON, IRN, and QR code.
• This data is integrated back into your ERP/invoicing system automatically (if API is used).
• You now have a legally valid e-invoice.

Step 6: Final Invoice Issued to Buyer

• You now print or email the final invoice with the IRN and QR code.
• The QR code must be printed on the invoice (mandatory).
• Without the IRN and QR code, the invoice is not legally valid under GST for B2B transactions.

Step 7: Automatic Data Sharing with GST Portal

The IRP automatically sends the invoice data to:

System	Purpose
GST Portal	Auto-populates GSTR-1 (sales register)
E-Way Bill System	Prepares Part-A of e-way bill (if applicable).

Recipient sees the invoice in:

• GSTR-2A / 2B (to claim ITC)

How PKC Helps Businesses With E Invoicing Under GST

✅ Expert GST e-invoice schema compliance and implementation

✅ Turnover threshold assessment for e-invoice applicability

✅ 24/7 technical support for e-invoice portal issues

✅ API integration for seamless e-invoice portal connectivity

✅ Credit note and debit note e-invoicing support

✅ Multi-GSTIN e-invoicing for diversified business entities

✅ Comprehensive training for your accounting teams

✅ Multi-location GST compliance management for enterprises

✅ Integration with existing Tally, Busy, QuickBooks software

✅ Proactive alerts for regulatory updates and changes

Explore Our GST Services here

Benefits of E Invoicing Under GST

Standardized Format: E-invoices follow a common schema, ensuring consistency across systems. This simplifies processing for auditors, tax officials, and software platforms.

Fewer Errors & Less Fraud: Each invoice is validated in real-time by IRP, eliminating duplicate entries and incorrect GSTINs. Invoices receive a unique IRN and QR code, making them tamper-proof and reducing fake invoices and ITC fraud.

Faster ITC Claims: Once authenticated, invoices auto-reflect in the buyer’s GSTR-2B, speeding up and simplifying Input Tax Credit claims.

Seamless Integration: E-invoice data auto-populates GSTR-1 and E-Way Bills, cutting down on manual data entry and saving time.

Lower Compliance Burden: Returns are auto-filled, reducing filing effort and mismatches between GSTR-1 and GSTR-3B.

Greater Transparency: QR codes on invoices allow instant verification by buyers and tax officials, boosting trust and credibility.

Better Cash Flow: Fewer disputes and faster processing lead to quicker payments and improved working capital management.

Easier Reconciliation: Auto-sharing of invoice data between buyer and seller reduces mismatches and simplifies audits.

Easier Access to Credit: Digitally verifiable invoices help banks assess creditworthiness, speeding up loan approvals and invoice financing.

Cost Savings & Efficiency: Automation cuts manual work, reduces errors, and lowers overall compliance costs while enabling faster audits.

E-Invoice Format and Schema

An e-invoice schema is a standardized JSON template that defines how invoice data must be structured when submitted to the IRP.

• It ensures uniformity in invoice reporting
• Required for IRP validation and generation of IRN (Invoice Reference Number)
• Eliminates errors in GST returns, e-way bills, and audit trails

Mandatory Fields in E-Invoice Schema

Field	Description
Supplier GSTIN	GST number of seller
Buyer GSTIN	GST number of  buyer
Invoice Number	Unique number, as per your accounting system
Invoice Date	Date of issue
HSN/SAC Code	Goods/Services classification
Taxable Value	Value before GST
Tax Rate	GST rate (e.g., 5%, 12%, 18%)
Total Invoice Value	Value including GST
Place of Supply	State/UT Code
Invoice Type	B2B, Export, SEZ, RCM, etc.

Optional / Additional Fields

• Buyer name, address, contact info
• Dispatch & delivery addresses
• Payment terms, credit period
• PO number, contract number
• Transporter details for e-way bill

Main Sections of the E-Invoice Schema (v1.1)

Section Name	Key Fields (Examples)
Basic Details	Invoice type, invoice number, invoice date
Seller Details	GSTIN, name, address, pincode, state code
Buyer Details	GSTIN, name, address, place of supply, pincode
Dispatch Details	Location of dispatch (if different)
Ship-To Details	Delivery address (if different from buyer)
Item List	Description, HSN/SAC, qty, rate, amount, taxes
Tax Details	CGST, SGST, IGST, Cess amounts
Document Totals	Total taxable value, total tax, grand invoice total
QR Code & IRN	Auto-generated by IRP upon validation

File Format 

Format: JSON (JavaScript Object Notation)

• Machine-readable
• Must follow latest schema version (e.g., 1.1)
• Generated automatically by ERP/software (not manually)

Schema Characteristics

• Strict data types (string, number, decimal)
• Maximum lengths and formats enforced (e.g., GSTIN = 15 characters)
• Version control (e.g., v1.1)
• Validation rules applied at IRP

Where to Get Schema Files

• GST E-Invoice Portal
• NIC Developer Portal
• Updated API documentation and sample JSON files are provided

12 Common Errors in E Invoicing: Reason, Codes & Fixes

Even though e-invoicing simplifies compliance under GST, errors can still occur. Let’s address the most common issues:

1. Duplicate Invoice Upload

Error Code: 2150

Reason: Same invoice (same GSTIN + Financial Year + Invoice No.) is being uploaded again.

 Fix:

• Do not re-upload an already submitted invoice.
• Use your accounting software to check if an IRN was already generated.
• Implement controls to prevent reusing invoice numbers.

2. Invalid JSON Format or Schema Error

Error Code: Multiple

Reason: Invoice not in the correct JSON format or using outdated schema.

Fix:

• Update your ERP or billing software to the latest GST schema version.
• Validate JSON before upload using GSTN-provided tools.

3. IRN Not Generated

Reason: Mandatory fields are missing or data mismatches (e.g., invalid HSN, wrong invoice type). 

Fix:

• Verify that all mandatory fields are filled (invoice date, GSTIN, HSN/SAC, tax rate, etc.).
• Use schema validators or automated pre-checks in your software.

4. Wrong GSTIN (Supplier or Buyer)

Error Codes: 3028 (not found), 3029 (inactive)

Reason: Invalid, inactive, or mistyped GSTIN.

Fix:

• Check GSTIN validity on the GST Portal.
• Implement real-time GSTIN validation in your billing software.

5. Missing or Incorrect HSN/SAC Code

Error Code: 2176

Reason: Invalid or insufficient digits in HSN/SAC code (e.g., 2 digits for turnover > ₹5 Cr).

Fix:

• Use the GST HSN Code Finder
• Maintain a master database of HSN/SAC codes in your system

6. Cancellation Errors

Reason: Trying to cancel an invoice after 24 hours.
Fix:

• Cancel invoices within 24 hours on IRP
• After 24 hours: issue a Credit Note and generate a new corrected invoice

7. Mismatch in Tax Values

Error Code: 2182, 2189, 2227
Reason:

• Total invoice value doesn’t match item-wise breakup.
• CGST ≠ SGST for intra-state supply.

Fix:

• Cross-check invoice math like discounts, rounding, and tax splits.
• CGST and SGST must be exactly equal for intra-state sales (±₹1 tolerance)

8. Invalid Document Type

Reason: Wrong entry in DocType field (e.g., using “Invoicee” instead of “INV”).

Fix:

• Use the correct codes:
  • INV – Invoice
  • CRN – Credit Note
  • DBN – Debit Note

9. Connectivity or API Errors

Reason: IRP not reachable, timeout, or too many API hits.

Fix:

• Retry after a few minutes
• Implement a delay/retry mechanism in your API integration
• Use error queues for failed requests

10. Invalid or Expired DSC

Reason: DSC used for signing not registered or expired.

Fix:

• Register or renew DSC via GST Portal
• Go to: Dashboard > Register/Update DSC

11. Data Mismatch Between IRP, GSTR-1, and E-Way Bill

Reason: Invoice data on IRP doesn’t match GSTR-1 or e-way bill.

Fix:

• Ensure all platforms (IRP, GSTR-1, e-way bill) pull data from a single source (ERP/Accounting software)
• Reconcile reports monthly

12. QR Code Not Printed on Invoice

Reason: IRN generated but invoice shared without IRP QR code.

Fix:

• Always print/share the IRP-generated QR code and acknowledgement number on the invoice sent to the buyer
• Invoices without QR code are legally invalid

✅ Do This	❌ Avoid This
Use updated GST-compliant billing software	Using Excel, PDF, or unsupported formats
Validate data before IRN generation	Submitting incomplete invoices
Cancel IRNs within 24 hours	Waiting too long to make corrections
Reconcile GSTR-1, IRP & e-way bill data	Manual entry in different systems
Train your staff on e-invoicing rules	Assuming system will fix errors automatically

FAQs about GST E-Invoicing