Tax changes to make it more attractive to give goods and professional time to charities could be made this year as part of the Prime Minister's drive to instil a "culture of giving".

The Government hopes to include changes allowing people and businesses to claim rebates for giving goods and services to charities in a tax legislation package due to be introduced after the Budget.

At present donors can claim rebates of one-third of donations - but it is restricted to monetary donations.

In a speech to Philanthropy NZ this week, Mr Key said he hoped that extending the rebates scheme to cover gifts of time and goods would encourage businesses which could no longer afford their usual donations or sponsorship deals to instead offer free hours of work to charities, or goods.

Revenue Minister Peter Dunne said officials were working on providing a similar rebate for "gifts in kind" rather than money.

One example was items such as artwork given to charity auctions.

The issue of whether a rebate could be claimed for time given to a charity was more complex. One possibility was distinguishing gifts of professional services from general volunteer work.

"Gift aid" is likely to be included at the same time - a process allowing people to ask for their rebates to be directed straight to a charity, rather than back to themselves.

Mr Dunne's work on the measures began under the previous Government and Mr Key committed National to continue with it in his speech to Philanthropy NZ.

He also called on people to give their tax cuts to charity if they did not need them, saying he wanted New Zealand to develop a strong, embedded culture of giving, akin to that he had seen in America.

Mr Key said that while New Zealanders gave as much as people in Australia and Britain, it was only half as much as Americans gave. The Government could make giving easier - and more attractive.

However, Mr Key's call for tax cuts to be given to charities has been criticised by other parties including Labour, the Green Party and Alliance - who claim the tax cuts themselves should target lower-income people, rather than relying on the wealthy to pass on their tax cuts to charities.

Child Poverty Action Group spokeswoman Susan St John also said Mr Key had his priorities wrong. She said it would be fairer if the Government gave better subsidies to low-income families rather than "relying on the philanthropy of the tax cuts recipients to solve poverty problems".

Labour leader Phil Goff said Mr Key's suggestion was a "guilt trip" for benefiting higher-income workers.

Mr Dunne said Mr Key's pledge to ensure the Government did what it could to help boost charitable giving was "very, very helpful".

He said he disputed Mr Goff's accusations that Mr Key was being paternalistic.

"I've had a strong view for some time that we do need to develop a culture of giving.

"All the changes we've been making have been towards that end and it's great to have the Prime Minister's backing. I think there is a huge capacity to do more."

As well as removing the cap for rebates on donations in 2007, legislation to allow workers to give directly from their payroll system - and simultaneously get the rebate paid - is before a select committee and expected to pass this year.