Tap in / tap out
What it really means
Touch your card on the yellow reader when you START a journey (tap in) and again when you FINISH (tap out). If you forget to tap out on the Tube or train, you are charged the maximum fare.
Context, tips & common mistakes
Two habits prevent nearly all overcharging. First, use the same card or device for the whole journey — tapping in with your phone and out with the physical card counts as two incomplete journeys, and both get charged maximum fares. Second, keep other contactless cards away from the reader ('card clash'), or the wrong card may pay. If you do get a maximum fare, it is not lost money: log the journey in a TfL online account or the TfL app, where you can review recent journeys and claim a refund for incomplete ones — occasional forgotten taps are refundable, though TfL caps how often. On buses you only tap in, never out. Watch for pink readers at some interchange stations: tapping a pink reader on a route avoiding Zone 1 proves you took the cheaper route and lowers the fare. If a gate is open or broken, still find a reader and tap — an open gate does not excuse a missing tap.