The Greens have announced the detail of a plan to phase out capital gains tax discount over five years, raising much more revenue than Labor’s plan to halve it.

Investors now get a 50% discount on the tax they pay on capital gains when selling an asset such as an investment property, a concession that costs the budget more than $6bn a year in forgone revenue.

Labor has said it will reduce that concession to 25% for assets bought after July 2017.

But the Greens want to phase it out completely, reducing the 50% discount by 10% every year for five years in parallel with the party’s plan to phase out negative gearing.

The Greens co-deputy leader and housing spokesperson senator for Western Australia, Scott Ludlam, said the plan would apply to all forms of capital gains including housing, art and investments.

“This is because tax on other forms of income, such as weekly earnings and interest on savings, receives no such discount, so we can’t see any justification for any part of capital gains to be tax-free,” he said.

The Greens plan has been costed by the parliamentary budget office and would generate just over $7bn by 2018-19, and $119.5bn over the next 10 years.

Labor’s plan, also costed by the parliamentary budget office would generate $565m over the forward estimates, and $32.1bn over the decade.

Both Labor and the Greens say their policies will slow the increase in housing prices, which should improve housing affordability.

But the prime minister, Malcolm Turnbull, argues that cutting the capital gains tax discount will hamper investment and economic growth and ending negative gearing for existing properties will “smash” house prices.

He says it amounts to “a tax on investment”, which will reduce much-needed investment in the economy.

And the coalition has also attacked Labor’s plan to limit negative gearing to new houses, from July 2017. Immigration minister Peter Dutton has said it would bring the economy to a “shuddering halt” and cause the stock market to crash.

Last week the chairman of the Committee for Economic Development of Australia (Ceda), Paul McClintock said raising capital gains tax or abolishing negative gearing would only have a marginal and manageable impact on investment.

McClintock said increasing capital gains tax “doesn’t mean it is a bad activity, but you can say there is too many billions of dollars going into that activity and we cannot afford that”. “How much support are we prepared to give to a particular activity?”

“With things like negative gearing, a system that was designed to compensate people for high inflation rates, the inflation rates are lower, there is a strong argument to suggest you can lower that and still produce an environment where people are willing to invest,” he said.

“Our judgment call is that, yes, of course it will have some marginal impact, so will everything, but it’s a manageable impact.”

The competing policies on the progressive side of politics to raise revenue from cuts to capital gains tax discount and negative gearing concessions come as the government insists it will not raise the overall tax take and that Australia does not have a “revenue problem”, but instead needs to been looming shortfalls in funding for health and education with other spending cuts.