Treasurer Joe Hockey has left the door open to cutting superannuation tax concessions, as pressure mounts from all sides for him to do so.

His comments come ahead of the April release of a taxation white paper that will recommend major overhauls to Australia’s taxation system.

When asked by Q&A host Tony Jones last night if he was planning to look at the issue of super tax concessions, Mr Hockey said: “On principle, it’s worth having a look at.”

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However, he went on: “The reason why I’m cautious is because it’s their money. I’m always cautious about taking people’s money off them.”

He repeated this statement a number of times.

When pressed again to say whether the government would tackle super tax concessions, he said: “Yes, if someone has got $12 million in their superannuation, that’s extraordinary if they’re not paying any tax on it.

“But that is not the rule, that is not the common situation. And what we’ve got to do is have a proper discussion … about how are we going to sustain our quality of life for longer.”

Mr Hockey’s failure to rule out cutting super tax concessions contrasted with his rejection of tackling tax breaks on negative gearing, on the contested grounds that doing so would raise rents.

His cautiousness reflects the intense pressure he will be under not to touch superannuation, in particular from the self-managed superannuation fund lobby, which has put the issue of super tax concessions at the very centre of its lobbying activities.

According to research by The Australia Institute, super tax concessions cost the government somewhere in the region of $30 billion a year, making it one of the second biggest budget costs. Those concessions go disproportionately to higher income earners.

Groups as diverse as the Greens, the Australian Chamber of Commerce and Industry, and even shock jock Alan Jones support a reduction in super tax concessions for the rich.