Labour leader Andrew Little is drawing the knives over the Government's refusal to reduce ACC's cash reserves.

In an announcement on Sunday, Little launched his party's campaign to stop the "rort", over ACC levies, that officials estimate would see the Government reap an extra $178 million in the next year.

Little said he would be working with businesses to pressure the Government to "cut ACC levies back to where they belong".

"The Government has got it wrong and every small business owner knows it," he said.

"National is cutting jobs and growth when it should be cutting ACC levies."

The Government is cutting levies, but by significantly less than what its own officials recommend.

Cuts in the levies worth $480m a year have been announced, but the Government rejected advice from ACC to offer overall cuts of $658m, documents from the Ministry of Business, Innovation and Employment showed.

ACC's three accounts were shown to be more than fully-funded.

At the last update, the earners account was at 137 per cent of full funding and the workers account at 133 per cent, against targets of about 117 per cent.

Most of the cuts adopted by the Government this year came from the motor vehicle account, even though at 103 per cent of full funding its ratio was the lowest.

The bigger cuts recommended by ACC would have sliced $119m off the Budget balance in 2014-15. The Government aimed to reach surplus this year, despite a forecast deficit.

Officials estimated the Government's refusal to cut levies faster would cost the average household $60 a year more, and small businesses with about 10 staff an extra $1500.

Big businesses employing 100 staff would pay more than $45,000 above the level recommended by ACC.

But an Infometrics report, released by Labour, said the Government was taking $350 million more than needed out of the pockets of businesses and workers.

Based on 2013 figures, the report showed the present levies cost up to 700 jobs.

"It's tough for Kiwis to get secure, well-paid work," Little said.

"As a country we need those jobs each year."

ACC Minister Nikki Kaye said Little's figures were out of date, and she was unapologetic about the Government taking a more conservative approach.

"There's a very important reason for that," she said.

"Labour left us with a $5 billion hole in ACC, and part of the reason for that is they didn't understand the bigger shifts that happen around the accounts."

Kaye said she supported a wider discussion about the long-term sustainability of ACC's accounts.

"The point is, we're dealing with a large amount of money in terms of our investment and our liabilities, and those things can bounce around a bit."