The commission released a report on vulnerable private renters on Wednesday.

It said the CRA had contributed to improvements on rental accommodation affordability but its indexation, based on the Consumer Price Index, had grown slower than rent prices.

The report presented data which showed the percentage of household incomes spent on rents outside of Hobart were around 25 per cent.

Hobart was at or above 30 per cent.

Housing stress is recognised when a household spends 30 per cent or more of its income on rent or a mortgage.

The paper found rental stress has increased since 2007-08 which could be attributed to an increase in the share of low-income households that rent, increased low-income households forced to rent in the private market, and ongoing population growth.

It said about half of private renter households in rental stress exit within one year, though households had increased prolonged periods of rental stress since 2001.

TasCOSS acting-chief executive Simone Zell said Commonwealth Rent Assistance should be increased to by at least $20 per week.

"Stagnant wage growth and long-standing underinvestment in social and affordable housing has led to severe rates of rental stress among low income households in Tasmania," she said.

Shelter Tasmania chief executive Pattie Chugg said two-thirds of low-income households lived in housing stress.

"Vulnerable households are paying nearly double the income level of other households," she said.

"Many low-income earners struggle to make ends meet and must make impossible choices between essentials such as food and heating and having a home.

"The report shows that that public housing has not kept pace with population growth and has pushed more people into the private market, and for many has entrenched disadvantage."