To start generating E-invoices on Refrens, the first step is to create a GSP username and password on the e-invoicing web portal.
Let’s see how you can do it step-by-step.
1. Go to the NIC E-Invoice Web Portal at - https://einvoice1.gst.gov.in/
2. Click on Login 
- If you are already a user of the E-way bill system, you can use your E-way bill username & password here.
- If you are not registered on the E-way bill portal, you will have to first register by clicking on the "Registration" tab highlighted above. After your registration, you will be able to generate a username and password. You can use the same credentials here.
3. After login, you will see a screen like this
4. Click on “API Registration”
5. Click on “User Credentials”
6. Click on “Create API User”
7. It will trigger an OTP to your registered mobile Number
Please enter OTP and click on Verify OTP
8. Click on “Through GSP”
9. Select “Vay Network Services Private Limited” as your GSP
10. Create API specific Username and Password and click on Submit
11. Please confirm acknowledgment from the E-Invoice System
12. Please use the newly generated User Name and Password at Refrens to generate E-invoices, click here for further instructions.
Additional Resources:
How to Generate E-invoices through Refrens? (India)
How to generate E-invoices for SEZ and Export? (India)
How to pass payment details to E-invoices? (India)
How to generate E-invoices for Credit and Debit Notes? (India)
How to show IRN in a single line in documents? (India)
How to view e-invoice acknowledgment no. & date? (India)
How to enable signed QR codes in IRN generated documents? (India)
How to fetch & update E-invoice status of the invoices generated/canceled outside of Refrens? (India)
How to cancel an E-invoice? (India)