Setting up the API system for e-invoicing

Application Programming Interface (API) enables taxpayers or their GSPs to interact with the e-invoice system. This article covers details about API registration in e invoice generation.

Latest Update

17th June 2026

The GSTN has released an advisory outlining changes to the APIs of the e-Invoice and e-Way Bill systems, effective from 1st August 2026. The Ship-to GSTIN would become mandatory in IRN & e-Way Bill APIs when Ship-to information is present ("URP" if the consignee is unregistered). In B2B/SEZ transactions, any Ship-to details entered during the IRN would not be overridden during e-Way Bill creation.

What is e Invoicing API?

API is an Application Programming Interface. Every taxpayer should ensure to obtain API registration in e invoice. API is a software intermediary which enables two applications to interact with each other. Under e-invoicing, APIs help in communication between taxpayers or their GSPs (GST Suvidha Providers) and the e-invoice system.

The API integration are of three types for API registration in e invoice –

1. Direct integration
2. Integration via GSP
3. Integration via a third-party software solution

Benefits of API integration in e-invoicing for a business 

Smooth data transmission

APIs facilitate the smooth transmission of data between the taxpayers’ accounting system and the e-invoice system. A taxpayer needs to just enter the data in its accounting software, and thereafter the APIs will transfer data to the e-way bill and GST portals and back to the ERP or accounting software. Following are the benefits of API registration in e invoice –

Lower manual intervention

API for e invoicing enables seamless integration of the ERP or accounting system of the businesses with the e-Invoice portal. The e invoicing api system facilitates the automatic or scheduled transfer of invoice details from the ERP to the e-invoice portal or the Invoice Registration Portal (IRP). One can avoid manual entry of data for reporting e-invoices.

Lower scope for errors

A one-time entry for obtaining e-invoices will also facilitate the generation of e-way bills and auto-fills most details in GSTR-1, thus avoiding multiple manual entries. Moreover, using API for e invoicing, taxpayer can avoid the manual submission of data. Accordingly, it helps the entity avoid data entry errors and transmission errors.

Other benefits

The taxpayer can enjoy a 24/7 self-help service from the e-invoicing system.

Prerequisite to keep in mind for API integration

Configuring the ERP/accounting software as per the requirements of the e-invoicing system is a must.

• The accounting software should be able to issue an invoice as per the notified schema of e-invoice. 
• It should allow smooth transmission of data to the e-invoice system via API.
• Invoices are printed after receiving IRN from the Invoice Registration Portal.
• The current solution should have a module for the storage of IRN. If not, then the taxpayer must arrange for one.
• Enable a pre-production system environment to test the e-invoicing integration. You can use the API e-invoicing sandbox.
• Adhere to the Information Technology, Act 2000, amended from time to time.
• Ensure your current billing/accounting/ERP system has a Secure Socket Layer (SSL) protection with at least the TLS 1.2 version.

Uses and actions to be taken on the API e-invoicing Sandbox testing portal

Uses- The e-invoicing sandbox system provides essential information to the developers for integration of e-invoicing operations by NIC-IRP through APIs with the taxpayers’ accounting system. The main purpose is to allow testing in a simulated environment.

The developer can understand the process involved in the preparation, encryption and decryption of the request payload. He can upload the request payload and then check the results. 

A developer can use the material available in the resource section to get himself familiarised with Invoice Reference Number generation among others. He can understand the attributes used in JSON and map it with their technical name, masters for the country, currency, port and state, General master, etc.

Actions to be taken on the API sandbox testing portal for e-invoicing

1. Registration by eligible taxpayers: An eligible API user can get himself registered in the e-invoicing sandbox environment. The registration can be done by taxpayers or GSPs, or software developers. 
2. Add GSTIN: Click on “Add test GSTIN” on the homepage. If the user is an eligible taxpayer, he can also create additional user accounts for other GSTINs under the same PAN.
3. Testing APIs in the sandbox environment: The developers can test the APIs and check the results, which could succeed or fail. Access to the e-invoice system will be provided after evaluating the Summary test report on the sandbox that is completed.

What is IP whitelisting, and how to set it up for e-invoicing?

IP whitelisting provides network access to specific IP addresses. Basically, it helps to control access to the e-invoice network.

Note that if a taxpayer is already integrated with the API under the e-way bill system, then the same credentials can be used for e-invoice as well. If not, the taxpayer can apply for IP whitelisting as mentioned in the topic below. The network team will scrutinise the IP addresses and whitelist the IP address.

Maximum number of IPs that can be whitelisted on the e-invoice portal and requirements

A maximum of only four public IPs registered in India can be whitelisted for IRN generation under the e-invoice system. Also, the request for all GSTINs should flow through these four IP addresses only.  

How to register API for e invoice for each GSTIN under the same PAN?

e Invoice API registration process involves the following steps-

Step 1: Log in to the e-invoice portal.

Step 2: Go to API registration and then click on IP whitelisting.

Step 3: After scrutiny of the test report, the IP whitelisting will be done.

Step 4: The client ID and client secret will be sent to the registered mobile number of the taxpayer via SMS. In case the same is not received, the taxpayer can log in to the e-invoice portal and click on resend. 

Note: These credentials are for a PAN that is the Company as a whole. So, all the GSTINs registered under the same PAN need to use these credentials. 

Steps to create multiple users under the same PAN

Follow the below steps to create multiple users for each GSTIN under the same PAN:

Step 1: Log in to the e-invoice portal and click on Create API user.

Step 2: On the API registration page, enter the client ID and client secret. Select the mode for registration with API as “direct” or “through GST Suvidha Provider”. In case the taxpayer selects GSP, he will have to update the name of GSP from the drop-down list and click submit. Here are the steps to select GST Suvidha Provider for e-invoicing.

Step 3: Now, create the username, password and re-enter the password and save it. The taxpayer can repeat the same process for all other GSTINs under the same PAN for which he needs separate credentials.