The Federal Government is working on a "mandatory code of conduct" that would guide negotiations between commercial landlords and tenants seeking rental waivers during the COVID-19 pandemic.
"If you sit outside the mandatory code, you are leaving yourself out in the cold," Mr Morrison told reporters in Canberra on Friday.
The code will be mandatory if tenants have a turnover of less than $50 million and are participating in the JobKeeper program.
That program requires businesses to have experienced a coronavirus-related downturn in revenue of 30 per cent to be eligible for wage subsidies.
"What is important as part of this code is that both parties negotiate in good faith," he said.
"There is a proportionality principle that needs to be in this code ... that the turnover reduction of the tenant needs to be reflected in the rental waiver of the landlord."
However, Mr Morrison said the code had not yet been finalised.
"[But] what we want to do is have landlords and tenants in the room to make sure they can work the issues out between them, to have the arrangement to get through this period and get to the other side."

St Vincent's Hospital in Sydney earlier this week. Source: Getty
He also said early modelling of the spread in Australia, which is yet to be released, was "promising and encouraging".
"We are tracking well, but we can't take that for granted."
Earlier this week, Mr Morrison announced a six-month moratorium on evictions.
Additional reporting: AAP
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