How can I cancel a tag on?

If you need to cancel a contactless tag‑on, wait at least 10 seconds after the initial tag‑on, then present the same contactless card or device to the card reader again. 

You can cancel a tag‑on up to 5 minutes after boarding a bus, provided the bus has not moved, or up to 40 minutes after tagging on to rail at a platform card reader.

If you try and cancel your tag on within 10 seconds, the platform card reader will say “fare already paid”.