Best Practices to Implement GST e- Invoicing API

GST e-invoicing API is an electronic solution that makes it easier to generate e-invoices for goods and services tax (GST) transactions in India using a uniform electronic format. This article covers details about e-invoice API, its benefits and users of e-invoice API.

What is e-Invoice API?

The e-invoice and Taxpayer/GSP systems communicate and share data using e-invoice APIs. RESTful APIs are accessible over SSL, and all transmitted data is encrypted. Only successful token-based authentication will grant access to the APIs. APIs that offer data based on specific inputs utilise the GET method, whereas those that receive data for addition or update use the HTTP POST method. The necessary credentials, including the client ID, client secret, user ID, and two passwords for the E-INVOICE SANDBOX SYSTEM (a testing tool for the creation of e-invoice APIs), must be obtained by eligible API users through a self-registration process. The authentication API must be called with these credentials to authenticate with the NIC’s e-invoicing API system.

Users of e-Invoice API

e-Invoice API is a tool that taxpayers and GSPs can use to comply with different GST regulations. There are several exceptions, though, including those related to QR code production and e-invoicing. Specific industries have received exclusions, including cinema tickets, insurance, banking, financial services, NBFCs, and the GTA. It implies that they are not compelled to create QR codes and e-invoices. The applicability and exception of e-invoice APIs are discussed above, and you can check e invoice applicability on the e-invoice portal. 

Purpose of using API under GST

The success of GST adoption depends on the convenience of taxpayers. It can connect to the GST filing system through third-party software that offers many interfaces on PCs, laptops, and mobile devices. By connecting via GST APIs, these third-party apps increase taxpayer convenience by interacting with the GST filing system.

e-Invoicing taxpayers will produce electronic invoices using the corresponding ERP software and submit them to the Invoice Registration Portal (IRP). The e-invoice process was built by the IRP using an API mode. The GSPs and taxpayers can create e-invoices straight from their system by integrating these APIs into their current ERPs. 

Benefits of using an API

  • APIs facilitate seamless integration between the taxpayer’s accounting and ERP systems and e-invoice software.
  • APIs prevent the duplication or double entry of an invoice or IRN since the outgoing supply invoices are first entered in the taxpayer’s ERP before being transferred to the e-invoice software.
  • APIs prevent the duplication or double entry of an invoice or IRN since the outgoing supply invoices are first entered in the taxpayer’s ERP before being transferred to the e-invoice software.
  • APIs assist in reducing data entry errors while generating e-invoices. 
  • The taxpayer needs to submit the information once in their ERP; the APIs will then send it to the GST and e-way bill interfaces.

Different types of e-Invoice API

Here are the different types of API for e-invoicing-

  • Authentication using any API 
  • Generate invoice Reference Number (IRN)
  • Cancel IRN  
  • Get IRN details 
  • Generate e-way bill by IRN
  • Get GSTIN details 
  • Cancel E-way bill
  • Sync GSTIN details from Common Portal
  • Get e-way bill details by IRN
  • Health API

Prerequisites for using APIs

  • Taxpayers and GSPs must automate the invoice generation process.
  • GSPs and taxpayers must ensure that no viruses, malware, bots, or other malicious software are present in the transmission that leaves their end and enters the e-invoicing system. Should NIC find any malicious traffic, it has the authority to halt the service.
  • The Government of India mandates that GSPs and taxpayers comply with all IT security standards and regulations.
  • GSPs and taxpayers should meet the security specifications for application and infrastructure provided by
  • The Information Technology Act 2000 and its revisions are mandatory for GSPs and taxpayers.
  • A list of at least four Indian Static IP addresses is required from taxpayers and GSPs to gain access to the production environment.
  • A pre-production testing system is necessary to use several services or activities. 
  • Taxpayers and GSPs must test their updated systems using a range of services on the e-invoice pre-production portal. 

Implementation of GST e-invoicing API

  • API Interface for Tax Payer Automated system – Taxpayers enter details of invoices into their automated system. The same information is submitted to the e-invoice “Generate IRN” API in the necessary format. An IRN is produced once the invoice is registered. The taxpayers receive this; an electronic invoice has been digitally signed, and a QR code must be preserved with the IRN and ACK Number. The invoice with the embedded QR code and IRN is ready for printing from the taxpayer’s system.
  • Store the response values – Include the ACK Number, ACK Date, IRN, and Signed-Invoice in your API method answers. It is suggested that taxpayers save this data with the request record in case they need it later. There will be no future reliance on these GST system data.
  • Validate the JSON Schema and data before requesting – A prerequisite to creating the IRN is the JSON Schema and data validations. Taxpayers are urged to have the JSON payload validated by the provided schema and the data validated by the validation processes. This will guarantee the final user receives faster and better service.
  • Check the response status and act accordingly – Every API response contains the data and status or an error. The taxpayers need the interface to handle them correctly. Get the data changed or repaired at the user or system level, resubmit the request if the status shows an error, and provide the list.
  • Don’t request the token for every transaction – The e-invoice system returns the token, SEK, and token expiration time during the authentication procedure. Using these data for every transaction is advisable instead of requesting them each time by storing them in the taxpayer’s system. This will expedite the transaction process and prevent the taxpayer’s e-invoice system from blocking the API service.
  • Re-generate the token before expiry – The e-invoice provides an authentication token valid for six hours. It is advisable to request a new token no later than ten minutes before its expiration. If any requests were unsuccessful over that period, reviewing them and trying again later is recommended.
  • Don’t store the e-invoice system’s SSL Certificate – The e-invoice system routinely updates the SSL certificate as per the security standards. Taxpayers are recommended against storing or hardcoding an SSL certificate in their API interface application.

The GST e-invoicing API is important for companies using the Indian GST system. With this technology, businesses can increase GST compliance, decrease errors, and automate and streamline their invoicing procedures. 

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