Unions ACT secretary Alex White came out swinging, after the construction and property sector said the current change of land use charge lacked "transparency and certainty".

The territory government raised the charge to change the use of land from a house block to a strata title from $7500 a unit for the first three units and $5000 a unit after that to $30,000 in last year's budget.

But despite the hike, the tax raised $14.7 million less than predicted last year.

Master Builders Association ACT chief executive Michael Hopkins said government should introduce a fixed charge on developments to provide more "certainty" about the level of tax to be raised.

Property Council ACT executive director Adina Cirson argued levying the charge up front would provide more "certainty" to both developers assessing the feasibility of a project and the government when forecasting revenue.

But Mr White said the construction and property sectors were getting a great deal regardless of the tax hike.

"The lease variation charge and its predecessor is one of the ways the public can realise the value the improvements and investments public money makes to local areas," Mr White said.

"The reason why developers want lease variations because the property is worth more and 99 times out of 100 it's because government invested in beautification and infrastructure, not private investors."

Mr White said it was "pretty rich" for the property and construction sectors to call for more tax cuts when they had also been at the forefront of lobbying for $80 billion worth of company tax cuts federally.

He said the lease variation take was always smaller than budgeted for because of the number of concessions the government gave out.

The ACT government failed to meet repeated deadlines last week for figures around lease variation charge concessions for the last financial year.

However the 2015-16 annual budget shows planning officials gave five partial waivers at 55 per cent and one full waiver.

Mr White also said the government did not check that developments granted concessions on environment and social grounds actually matched what was expected of them.

"I'm not saying every development doesn't meet the standards, I'm saying no one has checked," he said.

"We don't know how much money could have gone to fund more nurses, more walk-in centres and housing affordability instead."

The charge has been criticised as deterring infill, despite government saying it wants more people to live in established suburbs.

Last year's increase prompted developers to file 147 applications for lease variations between June 6 and June 30.

By comparison, a total of 243 development applications with lease variations were filed in 2016-17.

Chief Minister Andrew Barr has said he will  not consider revoking the charge, despite sustained pressure to do so.