Tag on and tag off for every trip
For each part of your journey, you'll need to tag on and tag off so that the correct fare can be calculated.
You'll need to tag on and off even when using a 30-day pass or child free pass, as the system needs to verify that your journey is included in your pass - if your journey isn't covered by your pass, then the balance on the card is charged as a normal fare. For example, if you have a 4-zone pass, but travel 5 zones on a journey, that journey isn't covered in the pass and the regular fare applies.
Snapper will automatically charge the correct fare based on where you "tag on" and "tag off" with your card. If you forget to tag off, you will be charged a default fare.
Where to tag on and off
When catching a bus, tag on at the front of the bus, and tag off before you exit the bus. Transfers between buses will apply as long as you tag on and tag off of each service within the 30 minute transfer timeframe.
When catching trains, tag on and tag off for each train trip using the Snapper reader on the train platform. Only if you're transferring between an express train and the next all-stopper train (on the same line in the same direction), don't tag off at the stopover station - only tag on at the first station and tag off at your final station.
Buses replacing trains (BRT) - When buses replace trains, tag on and tag off on the bus replacing the train - not on the platform. If it is not possible to tag on the bus that is replacing your train for any reason, you will still be able to travel.
When buses replace part of a train service, you'll need to tag on and tag off on the platform for the train, and also tag on and tag off on the bus replacing the train. (e.g. tag on at Upper Hutt platform to travel by train to Petone, tagging off on the Petone platform. Walk to the BRT bus stop, and tag onto the BRT bus as you board at Petone, tag off at Wellington as you exit the bus).