THE State Government has opened the door for new taxes, including environment and traffic congestion charges, as part of a review of state-based taxes to be completed over the next few months.

In a position paper released this week, the prices regulator IPART has outlined the case for broadening the tax base while abolishing more narrowly based, inefficient taxes.

At present, NSW raises $18 billion a year - nearly a third of its annual revenue - through taxes such as the payroll tax and property taxes.

NSW has consistently resisted Federal Government pressure to abolish more taxes, saying it would do so only if it received a fairer share of the existing GST tax carve-up with other states.

In its paper, IPART pointed to the possible introduction of an environment tax. In a separate paper on CityRail, IPART highlighted the need for congestion taxes to curb car use.

Taxes levied by the State Government are riddled with exemptions, making them inefficient due to their narrow base, IPART said. The payroll tax, for example, has a $600,000 threshold, while land taxes have an exemption for farmers. As well, taxes on poker machines in clubs are levied at a lower rate than on machines operated elsewhere.

The Opposition spokesman on finance, Mike Baird, said the State Government was planning to impose a GST. "If you read IPART's tax review, there is only one conclusion: throw out the present taxes and embrace a GST," he said.

A spokesman for the Treasurer, Michael Costa, dismissed this, saying the Commonwealth is the only government able to levy an excise.