I have a season for zones 1&2 and have added some pre-pay credit, and it has
successfully debited zone extensions when I've been into zone 3. (And,
correctly, no problem on buses out of zone.)

Note though (see other threads here!) that pre-pay doesn't work on most
National Rail lines.


"Ben Nunn" wrote in message
...
Thinking about my travel arrangements for a seven day period in the near
future, I think it might be marginally better value (than the
alternatives)
for me to buy a week zone 3 only travelcard (which includes all buses).
And
then pay pre-pay for my other journeys.

Would the system factor in the fact that I was already covered for zone 3
when costing my pre-pay journeys?

BTN