The Tenants Union of Tasmania has told a parliamentary committee an estimated 500 households could have been stung by rent increases before an order to freeze rents was introduced.
A freeze on rent increases until June 30 was enacted on April 23.
The union's principle lawyer Ben Bartl said the freeze should have been backdated to the start of the month.
He said this would ensure there was consistency with allowances given to commercial tenants.
Mr Bartl said the emergency period until June 30 should be extended by three months.
He said the median renter in Tasmania was already under rental stress before the coronavirus outbreak so would need additional time to make up rental arrears.
Mr Bartl said more than 520 households between March 27 and April 23 would have received rent renewal notices for this year, most of whom would have agreed to stay on by the union's estimate.
"Generally speaking, every year your rent does go up so approximately 500 households would have received rent increase notices," he said. Policy officer with the union, Alex Bomford, said landlords cannot be compelled to general repairs over the emergency period.
He said this could include rectifying faults, undertaking pest control, and repairing ovens.
Mr Bomford said this provision should be amended if the emergency period was extended.
Government minister Elise Archer said commercial and residential tenancy leases were distinctly different.
"In terms of residential tenancies, there have been packages available from both state and federal governments ... which have assisted tenants to meet their obligations," she said.
Ms Archer said subordinate legislation, used to freeze rent increases, could not be used retrospectively unless the enabling act allowed for it. The Tasmanian Residential Tenancy Commissioner has received five applications for unreasonable rent increases from March 1 to April 23.