Why do I need to have $1.25 on my Clipper Card if I'm riding Caltrain using a monthly pass or 8-ride ticket?
Caltrain fares are based on a zone-system, and you must tag your Clipper Card at the start of your Caltrain ride so the system can calculate your fare. If you do not you will be charged the maximum possible cash fare, which is $12.50. The Clipper system allows a negative balance of no more than -$11.25 before additional value must be added. Therefore you must have at least $1.25 on your Clipper Card.