The NSW government is still losing millions from its Opal smartcard scheme each year due to a loophole that lets people bin cards with negative balances.

This is despite introducing new conditions such as a $35 minimum top-up amount at Sydney Airport to prevent customers disposing of cards with particularly high negative balances.
In an annual audit of the government’s transport cluster released on Thursday, the state’s auditor revealed the amount lost due to negative balances on Opal cards was $2.9 million last financial year.
It represents 0.4 percent of all Opal card revenue collected by Transport for NSW during 2018-19.
While the figure is $0.9 million less than the negative balances of cards in the 2017-18 financial year, is also the second highest year for negative balances since the scheme was introduced.
As at the end of June 2019, the cumulative balance of negative Opal card balances was $10.4 million – $9.3 million of which was last over the last three financial years.
TfNSW has attempted to partly close the loophole - which allows users to tap off with a negative balance as long as they tapped on with the minimum balance required to travel – over the last year through new conditions
“In January 2019, Transport made a change to the airport stations to prevent customers with high negative balances exiting the station,” the audit [pdf] states.
“In addition, in late 2018, Transport increased the minimum top up values for new cards at the Sydney Airport stations.”
The auditor has again recommended that TfNSW “implement further measures to prevent the loss of revenue from passengers tapping off with negative balance Opal cards”.
TFNSW was able to claw back some of its lost revenue last year, with “approximately $200,000 ... recovered from prior year balances”, though this was likely to only be from registered cardholders.
“If a passenger’s card has the minimum value when they tap on they will be able to tap off and the card will go into a negative balance,” the audit states.
“Revenue from unregistered Opal cards with negative balances cannot be recovered unless the passenger tops-up the card.”