Parliament is close to passing the Government's tax cuts legislation, with the Labour Party fighting the bill to the last minute.

Opposition MPs say it will give big tax cuts to high income earners while those at the other end of the scale will be worse off than they would have been if the previous government's long-range package had been left alone.

The Taxation (Urgent Measures and Annual Rates) Bill also changes KiwiSaver and repeals the research and development tax credit introduced by the previous government.

When Parliament adjourned at midnight, MPs were halfway through the bill's third reading, its final stage, and were debating it under urgency.

Shortly after Parliament resumes at 9am it will be voted into law.

Finance Minister Bill English introduced the third reading debate, saying the provisions in the bill were known before the election and voters had supported it by putting National into power.

He said the bill was part of the Government's plan to get New Zealand through the recession with minimum damage.

It would stimulate the economy and provide incentives for people to get ahead.

"No one is worse off as a result of this piece of legislation," he said.

"This rubbish from the Opposition about low income people being attacked...if they're hard up it's because Labour ignored them for years."

Labour's finance spokesman, David Cunliffe, said the details of the tax cuts and other measures were not known before the election.

"Sheep's clothing has fallen from the National wolf," he said.

"Everyone has seen through this charade. We understand this for what it is."

Former finance minister Michael Cullen also said National had never previously debated the details of its package.

"All they talked about was tax cuts in the context of everyone getting one," he said.

"Let's not pretend National have a detailed mandate from the country for this."

The tax cuts will deliver $18 a week extra for a worker on the average wage when the first tranche kicks in next April.

Incorporating Labour's October 1 tax cuts, the same worker would be $47 a week better off by April 2011, when the whole programme is in force.

But Labour says those on incomes of between $14,000 and $24,000 will be worse off, and so will many modest income families with children.