A respected think tank says while a lifetime cap on superannuation contributions may sound attractive, it would only serve to benefit older, richer workers.
Treasury is reported to be considering a lifetime cap as part of the Turnbull government's tax reform package in an attempt to rein in bulging tax concessions.
But Grattan Institute boss John Daley says in practice it would only encourage people close to their retirement age to sacrifice up to all of their income to take advantage of a lower tax rate.
"At least at the moment we are capped at $35,000 (for salary sacrifice)," he told AAP on Monday.
A Parliamentary Budget Office analysis conducted for the Greens has also indicated that a lifetime cap won't generate enough savings to rein in the rising cost of superannuation tax concessions.
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Placing a lifetime cap of $500,000 on voluntary super contributions would raise only $165 million in savings over four years when tax concessions would amount to $170 billion over the same period.
Greens MP Adam Bandt says while it is good the government is considering super reforms, it is going to need to do far more "serious surgery" if money is to be raised to fund schools and hospitals.
The government repeatedly says everything is on the table when it comes to tax reform.
"But it's getting next to impossible to have a sensible debate about how to raise money in this country, because the government says everything is on the table but they're keeping the table in a closed room behind locked doors," Mr Bandt told reporters in Canberra.
