Auckland Transport is working harder to catch train passengers who are not buying tickets.
It won't reveal all the details of its strategy, but says fare evasion is simply theft from ratepayers and taxpayers.
The agency doesn't know exactly how much it is losing, but believes it could be 7% of commuter rail revenue, or more than $2 million per year.
Auckland Transport chair Lester Levy said gaps at stations would be closed or better monitored, and there will be more checking on board trains.
A new $10 penalty fare will be more rigorously imposed, and could rise later to twenty dollars.
Dr Levy won't rule out the agency seeking a law change to allow it to impose instant fines, if a softer approach doesn't work.