SuperGold Card travel costs are soaring as more people pick up the free scheme, and the Ministry of Transport says there is now a $4 million funding shortfall.
The card, which is available to pensioners and veterans, entitles users to a range of Government concessions, including free public transport during off-peak periods - 9am-3pm on weekdays.
Ministry chief executive Martin Matthews this morning told a parliamentary transport committee that the initial funding for the travel scheme was set at $18m in 2008.
"The level of patronage has grown significantly to where the actual cost of the scheme is somewhere around $22 million," he said.
Extra funding was provided two years ago, but Mr Matthews said consideration now needed to be given to a long-term solution to fill the funding gap.