Some of Australia's biggest property developers will be exempt from charges aimed at discouraging land banking in the ACT, which would have raised many millions of dollars.

But the ''commence and complete'' charges, hiked in 2008 under a restructured Territory Plan, still apply to home builders on standard residential blocks.

Builders failing to complete new homes within two years face charges and could be fined to discourage land banking, while the likes of QIC, owners of the Canberra Centre, Mirvac and Leighton Properties, sitting on vacant land in Civic, could have their fees waived. The Canberra Times understands some developers have already had the fee waived, including one on Kingston Foreshore for about $1 million, but the government won't confirm this, citing the Privacy Act 1988.

Treasurer Andrew Barr was applauded at a Property Council lunch two weeks after the June budget when he announced the government would waive the fee for commercial, mixed-use and multi-unit residential developments.

The announcement towards the end of his speech was made with little fanfare. Mr Barr said land banking before the global financial crisis had been resolved.

ACT Property Council executive director Catherine Carter said many developers had been stung by significant fees, and while the announcement was welcomed, developers applying for the waiver since Mr Barr's announcement were being fobbed off.

Ms Carter said some developers were exempt, while others were being punished.

The Property Council accused the government in 2008 of bungling the sharp fee increase in the first place, because it would catch out commercial developers who could not complete projects for reasons other than land banking. An example given was Leighton Properties and Mirvac Projects, who bought the huge Section 63 site on London Circuit for a record $92 million, and subsequently faced an extension fee of $8 million.

Then Planning Minister, Mr Barr, said the fee would not impact on the big end of town, because time was money and they would get on with developing their land.

But in the aftermath of a construction boom sites around the city have sat vacant because of tighter bank finance and scarcity of Commonwealth government tenants.

Colliers International has recently taken over the Section 63 leasing assignment, leading to speculation residential development may occupy a large slice of the 2.6-hectare site on London Circuit.

Colliers ACT chief executive Paul Powderly said people had bought sites in good faith from the government, only to be caught by the global financial crisis.

''So the government should not be capitalising on that misfortune and change of circumstances.''

Meanwhile, the government has issued 12 notices since April to owners of residential blocks to comply with their leases.

Environment and Sustainable Development Minister Simon Corbell's spokesman said three warnings had been issued to terminate crown leases.