ACT election 2020: Canberra Liberal promises to cost $1.1 billion, Alistair Coe reveals

Mr Coe described the Opposition's election commitments as ambitious, but said they were affordable and could be paid for by growing Canberra's population.

Chief Minister Andrew Barr has again questioned the credibility of Mr Coe's big spending agenda, saying voters would see through the "inherent contradiction" in the Liberals' promise to improve public services while lowering taxes.

His comments came as updated Labor analysis showed that a Liberal government would need an additional 137,000 ratepaying households in the ACT from next year to fund its promises.

A day after confirming the Liberals' promised residential rates freeze would cost the ACT budget about $160 million, Mr Coe revealed his party's full suite of commitments would drain about $1.1 billion from the territory's coffers over the four-year term.

Mr Coe also confirmed that the Liberals would borrow at the same level as forecast in the government's August budget update, meaning the ACT is on track to be saddled with about $7.7 billion of debt by 2023-24 regardless of which party wins next weekend's election.

The Liberals' package of policies includes promises to cut car registration, freeze commercial rates for two years, spend $120 million to cut hospital wait times and provide free before and after school care.

Speaking at Alpha Fresh Foods in Hume on Thursday afternoon, Mr Coe said the $1.1 billion hit was manageable given the ACT was projected to rake in about $26 billion in revenue over the next four years.

"It is an ambitious plan that we have for Canberra, but it is an affordable plan," he said.

"We are ambitious. Canberra deserves that ambition. Canberra deserves better than what we are getting."

Mr Coe said on ABC radio on Thursday morning that a team of economists, including people inside and outside the party, had provided advice on his plan to use population growth to pay for the promises.

Asked later in the day if he would release modelling to support the theory, Mr Coe claimed he had also already disclosed the "crux" of the argument through his repeated references to the amount of money being lost to the ACT as a result of housing estates in neighboring NSW towns.

At the press conference, Mr Coe also confirmed the Liberals would investigate opportunities for residential development at Kowen Forest and the grasslands west of the Murrumbidgee River near Tuggeranong if elected. He stressed neither would be redeveloped in the near future, with the possibility of housing in the Tuggeranong region "decades away".

Earlier on Thursday, Mr Barr called on Mr Coe to publish the modelling underpinning his theory, which he labelled "magic pudding economics".

"You can't simultaneously slash government revenues, claim to increase services and increase spending and not borrow," Mr Barr said.

"As further questions are asked of him each day in this campaign more of this crazy theory starts to unravel.

"When he's pushed for further detail as the media have been doing, and the community have been doing day in, day out, it becomes clearer and clearer that he can't deliver what he is promising and the inherent contradiction at the heart of their entire campaign is there starkly for everyone to see."

Labor has been tracking the Liberals' announcements throughout the campaign, analysing the level of population growth needed to pay for the expected cost of its opponent's policies.

Its latest modelling is based on the $1.1 billion figure quoted by Mr Coe on Thursday, although Labor believes the true cost of the Liberals' policies is about $1.4 billion.

The analysis found an additional 137,000 ratepayers would have to move to the ACT in the first year of a Coe regime to cover the $275 million revenue hole.

Projections in this week's federal budget showed the ACT's population was only expected to grow by about 1000 people in 202-21, and only about 10,000 in the next four years.