Total changes to New Zealand tax structure being contemplated by the government amount to a $3-4 billion package, says Prime Minister John Key.
In his first speech of the year to Parliament, he said a GST increase of up to 15 per cent is being considered after it was recommended by the Tax Working Group.

He says increasing GST to 15 per cent will bring in an extra $1.9 billion, once automatic adjustments to benefits and superannuation payments are factored in, which leaves another billion or two to come from other taxes.
John Key confirmed there will be changes to the way property is taxed, but didn't say when they will be introduced. They are widely expected to be part of the May budget.
He ruled out a land tax, a capital gains tax, and a tax that will set a flat rate on the value of equity in investment properties.
He said a land tax will fall only on people who hold their wealth in a particular form and will cause financial strife for those on low incomes. A capital gains tax will extend the tax net, but make the tax system 'more complex to administer and comply with”, while a flat tax on equity – known as the risk-free return method – will hit tenants with higher rents.
His speech doesn't rule out ending of tax breaks available through depreciation, which the Tax Working Group says will give the government an extra $1.6 billion a year.
Also left open is the prospect of ending the ability of investors to write off losses on property against other income.