Above-average budget change if Labor wins

A change of government at the upcoming federal election would have a greater impact on the budget than a typical national poll, according to a leading economic forecaster.

About six per cent of the federal budget laid out by Treasurer Josh Frydenberg earlier this month would change if Labor wins the May vote, Deloitte Access Economics says in its latest Business Outlook.

Usually major parties in opposition propose changes that would impact less than two per cent of the budget.

The higher-than-average impact comes as Labor is proposing big major reforms, such as changes to the negative gearing tax break for property investors.

Labor has vowed to keep negative gearing only for newly-built homes from January 1, with the policy grand-fathered so that people already capitalising on the measure are unaffected.

The opposition has also promised changes to capital gains tax, would ditch cash refunds for Australian shareholders with "excess" franking credits and wants to reform family trusts.

The reforms would reduce the size of the Australian economy by subtracting about 0.33 per cent from Gross Domestic Product, Deloitte expects.

But Deloitte partner Chris Richardson says that trend would come with some "offsetting benefits".

"Greater spending on education and health, for example, would help to generate a fairer society," he said in the outlook released on Monday.

The large-scale impacts of the changes also depend on when they are enacted if Labor wins office, Mr Richardson said.

For instance, if Labor's spending measures cleared parliament before its tax reforms, it could provide a short-term stimulus at a cost to the budget's bottom line.

But Mr Richardson expects Labor would want to make the tax changes first, so they're further back in the rear view mirror when the next election arrives.

A change in government would cause a blip in job gains, with longer-term impacts through the re-regulation of the job market.