Nearly half of all Australian landlords have negatively geared properties, according to new figures that show the highest earners are hauling in tens of billions of dollars from tax concessions and loopholes.

Capital gains tax concessions will "cost" the federal budget $75 billion this year, and super tax concessions another $51 billion, according to Treasury's annual tax report.

As in previous years, most of the benefit will go to the highest earners. For instance, the top tenth of tax filers will account for $4 of every $5 claimed this year via the capital gains tax (CGT) discount.

That discount, which lowers the rate of tax paid when houses and shares are sold, has often been a target for tax reformers, who say it is inequitable and overly generous for its purpose, which is to adjust for inflation.

Labor vowed to halve it at the 2016 and 2019 elections, together with a promise to rein in negative gearing, which allows landlords to write rental losses off their tax liabilities.

Reform advocates say negative gearing and the CGT discount combine to make housing investment an attractive vehicle to minimise tax, if landlords use rental losses to slash their income tax and then make the losses back when the property is sold.

Treasury estimates the CGT discount will cost the budget $23 billion this year. Rental deductions will cost $27 billion although only a fraction of this is likely to be from negative gearing.

The number of landlords negatively gearing is 1 million, down from 1.1 million in the last financial year. The figure accounts for 42 per cent of renters.

These "cost" figures reflect how much money the government would have collected if the concessions did not exist. They do not reflect a government policy to change the rules, which Labor all but ruled out for negative gearing and CGT earlier this year.

Tax concessions for trust funds will cost $23 billion, while GST exemptions for fresh food, health and education will cost $22 billion.

The top tenth of tax filers — those with taxable incomes over $136,700 — reaped more than half of the tax benefit from trust funds and franking credits, and more than one-third of the benefit from super tax concessions.

Treasurer Jim Chalmers said the report was "an important piece of analysis" but added it was "not a statement of policy intent."

"I encourage you not to read too much into additional policy steps," he said.

EDITOR'S NOTE (17/12/2024): A previous version of this story stated that CGT concession cost $52 billion and the CGT discount cost $27 billion. These figures have been corrected to $75 billion and $23 billion, respectively.