Treasurer Joe Hockey wants to impose a 2 per cent tax on taxable incomes over $180,000 from July, taking the top ­marginal tax rate to 49 per cent.

But the tax on fringe benefits will stay at 47 per cent until April, presenting a nine-month arbitrage opportunity that hasn't been lost on tax advisers.

"Taxpayers will take advantage of it simply because it is so easy to do," said Prosperity Advisers tax director Stephen Cribb.

"People simply increase the non-cash-benefits component of their package during those nine months to bring their taxable income to below $180,000. It is particularly convenient for anyone thinking of rolling over to a new car," he said.

Someone on $200,000 could package the $20,000 cost of a new car lease over those nine months. This reduces their income to $180,000, and the debt levy does not apply.

"Every dollar that moves into the package is a dollar that does not attract the 2 per cent levy," Mr Cribb said.

PwC partner Kel Fitzalan said the mismatched start dates "will inevitably lead to tax rate arbitrage consequences, which may encourage employees to assess their salary sacrificing arrangements in the short term".

"This will provide more even more incentive for private businesses to accumulate profits which are subject to the corporate tax rate," he said.

Institute of Public Accountants senior tax adviser Tony Greco said salary packaging might come back into vogue. "We are hoping Treasury's forward projections have taken into account changes in individual behaviours, as taxpayers with incomes over $180,000 generally have access to good advisers," he said.

Mr Greco said tax planning could also occur around the differential between top marginal tax rate and corporate tax rate, which drops to 28.5 per cent come July 1, 2015. "The differential will increase to 20.5 per cent, representing an enticing opportunity for individuals able to restructure," Mr Greco said.

CPA Australia's head of policy, Paul Drum, said: "The government's planned three-year debt levy is in fact a two-year debt levy for some who avail themselves of smart tax planning. I'm not sure if this was intended at all. We'd be surprised if this anomaly makes it through the legislative drafting process."

But Grant Thornton tax partner Elizabeth Lucas said high-income earners generally look for big savings if they are going to bother with salary packaging. She did not think there would be a salary packaging frenzy.

And Pitcher Partners' Peter Braine said the change will increase tax paid by people earning less than $180,000 who salary-sacrifice.

This means anyone salary-sacrificing cars – teachers, sales people and senior management – may need to review their salary packaging arrangements," Mr Braine said."We suspect that there will be far more people inadvertently affected on lower incomes by this attempt to stop higher-income earners manipulating the system."

Institute of Chartered Accountants head of tax policy Michael Croker said those who can salary-package can achieve better tax outcomes than others when tax rates change.

"From a tax policy perspective, it's another illustration of why we need tax reform rather than tinkering with the income tax law through one-off, temporary levies," Mr Croker said.

KPMG remuneration specialist Ben Travers said the increase in the top marginal tax rate is likely to lead to individuals considering investment strategies, including negative gearing, or salary-packaging prior to the FBT rate increasing.

The same opportunity arises again from March 31, 2017, to the end of the three-year levy on June 30, 2017, if the Abbott government proceeds with its budget announcement.

smh.com.au