On April 9, then-federal assistant minister Sussan Ley approved new planning rules designed to pave the way for more than 37,000 new dwellings along Northbourne Avenue and Federal Highway in the coming decades.

The new rules allowed buildings of almost 50 metres in height on land at the Macarthur/Wakefield intersection, and cleared the path for housing estates around Kamberra winery and Yowani Golf Club.

The plan also set new design guidelines for apartments.

But three months on, the authority has acknowledged that further changes are needed to clarify which rules apply to development applications lodged with the ACT government before the plan was approved.

A spokeswoman for the authority could not provide details on the number or nature of applications affected, saying only that the decision to make the tweaks had been made "in the interest of fairness".

The most significant of the proposed changes, which will be released for public consultation on Wednesday, would require the ACT Planning and Land Authority to assess applications submitted before April 9 under the old rules.

The amendment would also clarify the maximum length of a development allowed along the corridor.

A report outlining the changes stated that some "uncertainty had arisen" as to whether the 55-metre limit applied in situations where each element of a multi-building development was connected to the same underground carpark.

The length limit would only apply to above-ground structures, under the proposed changes.

The authority also intends to clarify design rules for balconies and balustrades.

The process to establish new planning rules for the corridor has been protracted and, at times, contentious.

The ACT's peak business, property, planning and architecture groups united in opposition to the draft proposal, which they feared would constrain development along the corridor.

Further changes were made before the final plan was approved, which the groups largely welcomed.