Updated 6/3/2015 for new 2015 fares
Due to the way Opal implements minimum required balances for travel, it’s possible for your Opal card to fall into having a negative balance.
To travel with Opal, all that’s required is the minimum balance at time of tap on.
The minimum value to tap on with Opal depends on the time of tap on and the mode of transport. For trains, the minimum balance is $2.36 during off-peak and $3.38 during peak hours. For ferries it is $5.74 and for buses or light rail, $2.10.
Of course, you will need to top up again in order to use the card, but once you’ve tapped on, you can travel anywhere and tap off.
With the announcement that now you can purchase an unregistered opal card from a retailer with as little as $10 cash, this makes this option slightly more feasible.
An interesting side effect of this, is being able to get out at the airport train stations, and leave with a balance far lower than what you tapped on with.
The airport gate access fee is
$12.60 $13 for Adults (full fare) and $10.60 $11 for Child/Youth (or half fare/concessions).
This means that you can tap on from the city with as little as
$2.31 $2.36 off peak, and tap off at the airport, leaving you with a balance of -$12.60 -$13.00.
It’s even greater if you travel from a further fare band, such as Newcastle; you still only need the minimum to tap on, but because you pay for distance in addition to the airport access fee, you can be charged
$5.60 $5.81 (off peak) or $8.10 $8.30 (in peak) for your train, and then an extra $12.60 $13 for the airport.
This means you can tap on with
$2.31 $2.36 at Wollongong, alight at Sydney Airport, and leave with a balance of -$16.29 ($2.31 minimum – $5.60 train + $12.60 airport fee).
-$16.45 ($2.36 minimum – $5.81 train + $13 airport fee)
Of course, this only helps on your way to the airport – not on the way back.
But, if you’re stuck with an Opal card with only a few dollars, here’s an interesting quirk that may be of interest.