It is your responsibility to check that pay as you go with contactless is available at your destination before you touch in at the start of your journey. If you do not touch out, this will show as an incomplete journey, and you will be charged the maximum fare.
If you do not have a valid ticket for your whole journey, you will be liable to pay a full fare or penalty fare.
The penalty fare is £100 plus the price of the full single fare applicable for your intended journey. If it is paid within 21 days, the Penalty Fare is reduced to £50 plus the price of the single fare applicable.