Landlords will be able to lodge applications for rebates on their commercial rates bills from Tuesday - more than five weeks after Chief Minister Andrew Barr spruiked the measure as part of the government's second coronavirus support package.

The announcement came after Attorney-General Gordon Ramsay signed off on a temporary code of conduct for commercial tenants and landlords, which will implement principles agreed to early last month by Prime Minister Scott Morrison's national cabinet.

The code will force landlords to negotiate "in good faith" with any tenant who cannot afford to pay rent amid the downturn, before they can move to evict them.

In a joint statement, Mr Barr and Mr Ramsay said commercial landlords would have to ensure they were doing "everything they could" to help businesses survive the crisis.

The code hasn't been enshrined in law, although the pair said that step might have to be considered if the government's approach did not "drive a strong behavioural response".

Landlords, many of whom have seen their commercial rates skyrocket in the past few years, have been crying out for tax relief so they are able ease the pressure on their struggling tenants without financially crippling themselves.

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Under the scheme, the ACT government will offer rates rebates to commercial landlords who reach an agreement with their tenant to reduce rent.

Landlords whose tenants have effectively been forced to shut down due to the economic crisis will be offered the most support.

In those cases, the government will provide a rebate which is equal to 50 per cent of the amount they have taken off their tenant's rent bill.

Rebates would be capped at $8000 per quarter for landlords whose commercial units are valued at below $2 million, which is about 94 per cent of all properties in Canberra.

The Barr government had already granted a $2260 rebate to those landlords in the first tranche of its economic survival package.

For the worst affected owner-operators, the government will provide rebates equaling 80 per cent of their bill, up to a maximum of $8000 per quarter.

Applications for larger tenants - such as Canberra Centre - will be managed on a case-by-case basis, in line with the principles of the code.

The scheme will run for six months, with payments backdated to April 1. Landlords and tenants can agree to a rent reduction for a shorter period of time.

It was expected to cost taxpayers about $25 million, although the figure will depend on how many landlords sign up.

The code was expected to expire on September 30.

The delays in rolling out payments prompted criticism over the weekend from Canberra Liberals leader Alistair Coe, who said struggling businesses had been forced to wait too long for clarity on what financial support they could access.

"Given many property owners have waived or reduced rent or are in discussions, an understanding of whether they will get a rates waiver or reduction is vital information," Mr Coe said.

"Many businesses doing it tough are reaching the point of no return.

"We need to do absolutely everything we can to help local businesses survive the crisis and bounce back strongly."

The ACT government is putting the delays down to the time it took to nail the specifics of the scheme, which were refined in consultation with industry groups and property law experts.

New facts sheets for business owners will be published on Tuesday, which are designed to spell out their rights and obligations under the code of conduct in relatively simple language.

Brendan Smyth, who has been seconded to the position of local business commissioner during the COVID-19 crisis, will continue to provide a free and voluntary mediation services for commercial tenants and landlords.

Mr Smyth has already mediated 40 disputes with "positive outcomes for both parties", according to the government.