Hundreds of millions of dollars in tax relief for businesses to help them through the recession will be unveiled tomorrow by Prime Minister John Key.

Mr Key will outline policies aimed at helping out small and medium sized enterprises.

He will then send Parliament into urgency next week to pass them so they can come into effect at the start of the tax year on April 1.

Mr Key said the changes would not be insignificant and when asked if it was in the hundreds of millions replied "yes".

Parliament resumes for the year next Tuesday and will sit under urgency on Wednesday and Thursday. The Government will allow question time to go ahead despite the extended sitting hours.

Other legislation will also be debated under urgency.

Mr Key is to give a speech in Auckland tomorrow outlining the Government's plans to help small and medium businesses weather the rough economic climate.

There will be a range of initiatives aimed at taking pressure off the sector.

Changes will focus on tax, cash flow and regulation and are expected to include reduced penalties for companies which underpaid provisional tax.

The tax is paid in advance based on estimated earnings. Underpayers get hit with a 14.24 percent penalty.

Another likely change is to remove the presumption that profits will increase 5 percent on the previous year for calculating provisional tax.

The speech comes as Finance Minister Bill English and his Australian counterpart Wayne Swan meet to talk about the deepening impact of the financial crisis on trans-Tasman economies.

Australia is planning a further substantial official interest rate cut and another federal government stimulus package.

Mr English said while the two countries shared some problems, they would take different approaches and governments had to strike a balance between fiscal stimulus and debt.

He would talk to Mr Swan about banks and how to provide better public services when tax revenue was reducing.

Mr English wanted progress on the single market idea.

Labour Party finance spokesman David Cunliffe said Australia had been actively tackling the problem while the new National Government had taken a hands-off approach.

As part of measures to stimulate the economy -- as new figures showed the Australian budget would be at least $A15b a year in deficit for the next four years without new spending -- Prime Minister Kevin Rudd's government was looking at giving home owners free ceiling insulation, with subsidies for rental owners.

The package would be Australia's second stimulus package; the first was announced in October.

Mr Key said the Government had scrapped its predecessor's' plans for a $1b spend up on insulation but hinted some of the idea might survive.

"Part of what you will see from us around our infrastructure is an attempt to address a number of different concerns that we have," Mr Key told reporters.

"For instance, if we were to undertake areas of housing, insulation being an example, I think there's a number of wins that we can get there.

"One, it's scalable across the country; two, you've got a situation where you've a workforce that's ready to do that -- the construction sector's been slowing down so there's capacity; thirdly, you do get health and social benefits; but fourthly, you get environmental benefits."

Mr Key said infrastructure spending would be targeted at projects that had multiple benefits and long-term gain.