The Accident Compensation Corporation (ACC) says it is now essentially fully funded, paving the way for significant levy cuts next year.
ACC's annual report shows a net surplus of $2.1 billion - $298 million ahead of budget.
The corporation is attributing the result to stronger earnings from its international investments.
It said it accepted 1.8 million new claims during the 2013-14 financial year - up 4.7 percent on the year before - and is hiring extra case managers to deal with the growing workload.
In August, the Government announced it would cut ACC levies in the middle of next year, slashing the cost to most vehicle owners by about $135 a year.
Labour ACC spokesperson Iain Lees-Galloway said the Government was using ACC as a cash cow, and today's results showed the Government could go further.
"Every single New Zealander, every single employee, every single employer, every family driving their kids to school every day, is paying too much in ACC levies just so that the Government can pretend they've got a fiscal surplus."
ACC still had a long way to go to earn the public's trust and confidence, Mr Lees-Galloway said.
ACC Minister Nikki Kaye said the numbers were better than expected, and there could be more levy reductions in the future.
She said she would speak with ACC's board about the funding policy in the next couple of weeks.