Rail fares and other fees could amount to an extra $20 million per year for ratepayers in Auckland, as the Government moves to shift more of the rail network's costs off its books.
A report to Auckland Regional Council members says they should not sign a cost-sharing charter for new trains until there is more certainty over how big the bills might be.
The region also faces higher annual costs to use KiwiRail's tracks, but a working group will take several months to try to agree on what those costs could run to. The group's report is due in September.
The chairs of both the ARC and the Auckland Regional Transport Agency want to meet Transport Minister Steven Joyce.
Mr Joyce has publicly stated that Auckland and Wellington are not paying their way at present and KiwiRail needs a better return.