It's understandable that the new Treasurer, Scott Morrison, should want to rule out increasing the Medicare levy as an answer to the states' health budget problem, but it would be unrealistic of the Turnbull government to expect that the tax reform package can exclude other politically unwelcome changes to the income tax system.

Winning public support for pro-growth tax reform will be hard enough without the government trying to defend loopholes such as the use of trusts for tax avoidance and tax subsidies for the private use of executive cars.