The way it works at my place of employment is that I opt in a specified amount each month, and it’s taken out of my paycheck before taxes get taken out and loaded onto a card that I also happen to share with my FSA money (which is also pre-tax). With that card, I’m able to pay for all my public transportation. It’s been really great because it’s money I already set aside and don’t have to worry about having enough money for the train each month!