How does FASTag calculate charges for round trip ?

FASTag is designed to pass the benefits of round trip savings automatically.

Toll charges are different for a single trip (i.e pass a specific toll once) and for a round trip (i.e passing a specific toll plaza twice in the stipulated time). This is how it is calculated. 

If the round trip happens within the stipulated time (it varies from toll to toll), then the FASTag automatically deducts only the difference during the return trip. For example, if single trip costs Rs. 30 and a round trip costs Rs. 45, then the following happens

• The first time a customer crosses the toll, Rs. 30 is deducted from the FASTag. 
• When the customer comes back, then the difference between Rs. 45 and Rs. 30, which is Rs. 15 is deducted. 
• If the customer crosses the toll again, then s/he is charged Rs. 30. 

The stipulated time period might vary from toll to toll. 

• Some tolls have a 24 hour period from the time the customer crosses the toll and comes back
• Some tolls have a cut off time at 12 midnight
• Some tolls have a cut off time at 12 noon

Not only does FASTag save time and cash problems during travel, but it also gives the benefit of savings calculated automatically. Get your FASTag now !!

Source : https://fastag.brokerage-free.in/faq/fastag/how-does-fastag-calculate-charges-for-round-trip