The ACT government's long-awaited strata reform package, to be unveiled on Monday, also proposes changes to allow owners corporations and developers to choose how levies and contributions are distributed among property owners.

The first tranche of the package, which has been almost three years in the making, will be introduced progressively into the ACT Legislative Assembly in the coming months.

It will include measures targeting buyers, developers, owners corporations, businesses, households and pets.

The reforms will refresh outdated laws governing apartment and mixed-used developments, which are springing up across Canberra at a record rate.

Under one proposed consumer rights measure, developers and real estate agents would be compelled to notify buyers when "significant" changes were made to proposed developments.

The change would go some way to rectifying what Greens crossbencher Caroline Le Couteur described at June's budget estimates hearings as a "flaw in the legislation".

Ms Le Couteur was concerned to learn the ACT government had no system to ensure buyers were made aware when developers sought to make changes to developments which had already been approved

She claimed developers used amendments as a vessel to reintroduce aspects of projects which had been objected to, and removed, before approval was granted.

The proposed change would also give buyers "clearer rights" to cancel sale contracts if a project was changed significantly.

Buyers would also be given more information upfront about levies, maintenance schedules and other uses in their buildings - such as retail or commercial spaces - as part of reforms.

In another planned change, developers and owners corporations would be given freedom to determine how strata contributions and levies are divided up among owners.

At present, owners pays the same fees regardless of how often they use their building's utilities and facilities, such as water and lifts.

The government believes that more "accurately" splitting utilities costs between businesses and households in mixed-use development could result in lower bills for residents.

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The package, which the government has dubbed "Managing Buildings Better", also proposes measures to make it more difficult for developers and builders to vote at owners' meeting on matters relating to construction defects.

The Canberra Times has been told of situations in which developers, builders and sub-contractors, who own units in a complex, have joined forces to use their numbers to block the owners corporations from taking action to have defects rectified.

Developers would also be required to prepare plans that outline running costs and maintenance requirements, as part of the proposed reforms.

The process for owners to obtain approval to have a pet in their apartment would be made "clearer and easier", under another change.

The government said it had consulted with industry and community stakeholders to prioritise the reforms that would have the most "direct and immediate impact".

Senior ACT government ministers Gordon Ramsay and Mick Gentleman are scheduled to launch the reform package on Monday morning.

"As Canberra grows, we are seeing more and more people choosing to live in mixed-use developments in our town centres," Mr Ramsay said.

"The current legislation needs to be updated to keep pace with our growing city and the proposed changes will support great outcomes for people and businesses."