How to buy FASTags
A customer can visit any of the Point of Sale (POS) locations at toll plazas/ issuer agency to get FASTag account created. Apart from toll plazas, FASTags are available in banks which the authorities have signed up with. For a traveller to get the tag, he or she can approach those specific banks.
Currently, there are many private and public sector banks which have partnered with the NHAI. HDFC Bank, ICICI Bank, Syndicate Bank, Axis Bank, IDFC Bank and State Bank of India are among them. Among the payments banks, Paytm offers FASTag to its buyers.
FASTag mandatory for new four-wheelers from Dec 1: What is FASTag and how can you get one? - Moneycontrol.com