Are there any restrictions using the Oyster card on National Rail?
Only if you use pay as you go, because on most overground lines it is not valid. If you touch in or out on rail line that does not support pay as you go then the rail company will take £5.00 off your card for entering / exiting the area without a valid ticket. If you only have £1.50 pay as you go on your card that means you go £3.50 into debit.
Only if you use pay as you go, because on most overground lines it is not valid. If you touch in or out on rail line that does not support pay as you go then the rail company will take £5.00 off your card for entering / exiting the area without a valid ticket. If you only have £1.60 pay as you go on your card that means you go £3.40 into debit.