Labour is calling for an immediate cut to Accident Compensation Corporation levies after ACC's annual report revealed a surplus of $4.9 billion.
The Government has already signalled there will be some cuts, but Labour says there's room to slice $2 billion from levies.
Opposition ACC spokesperson Iain Lees-Galloway said the corporation's big surplus was gouged from the pay packets of hardworking New Zealanders.
He said the Government talked up a "phoney' ACC financial crisis four years ago so it could push levies to artificially high levels.
Mr Lees-Galloway said Labour is also critical of ACC cost-cutting through restrictions on claims and client resources.
ACC says its big surplus was boosted by strong investment returns, and better client management.
But Tony Gibbons, an advocate for ACC claimants, says a "tough love" strategy to get people off ACC means the corporation is not meeting its obligations.
ACC Minister Judith Collins has welcomed the corporation's financial progress, saying it allows the Government to signal $300 million worth of levy cuts.