e-Invoice is a system in which B2B invoices are authenticated electronically by GSTN for further use on the common GST portal. Under the electronic invoicing system, an identification number will be issued against every invoice by the Invoice Registration Portal (IRP) to be managed by the GST Network (GSTN).
Under this system, a unique IRN (Invoice Reference Number) gets issued by the IRP (Invoice Registration Portal) against every invoice generated. All the invoice details get transferred to both the GST portal as well as the NIC (National Informatics Centre) portal in real-time via APIs. This eventually eliminates manual processing and helps businesses to file GST returns and to claim GST refunds with ease.