Abolishing workplace-related tax deductions in return for lower rates of income tax, and targeting superannuation concessions at the high end, are now at the centre of the federal government's plans to pay for tax cuts which will be smaller than intended due to the decision to leave the GST rate untouched.

The idea to trade away tax deductions, advocated by Malcolm Turnbull when he was a back bencher and recommended by the Henry Review, could free up about $5 billion a year in revenue which, alongside changes to super, could still generate enough income for a modest cut to personal and company income tax.