The ceiling for homes subject to rent control will rise on January 1.

The Rent Increases (Domestic Premises) Control Amendment Act 2009 was passed in the Senate yesterday, meaning that any residence with an annual rent below $27,000 a year is subject to rent control. The current ceiling is $24,600.

Government Senator Marc Bean said the purpose of the change was not to increase the number of rent controlled homes, but to maintain it.

"The rental economy for the working class is extremely tight," he said.

Rising rental costs have resulted in 2,000 homes breaking the existing limit, resulting in the number of rent controlled homes dropping to 14,700. The legislature will increase that number to 16,800.

Opposition Senator Suzann Roberts Holshouser supported the legislation, and called for more people to work with the Rent Commission to make sure everyone was getting a fair deal.

"It is up to us to understand that while there are people out there trying to get as much money as they can, the Rent Commission is there to make sure you are protected," she said.

Independent Senator Joan Dillas Wright agreed, saying: "If you are a tenant and your landlord attempts to increase your rent arbitrarily, it is unlawful."

While Senator Walwyn Hughes questioned if rent for low end homes might have dropped along with the cost for middle and high end homes, Senator Bean said the price drops didn't affect the lower cost premises.

"On the low end there is always a high level of demand," he said. "This legislation is to protect the common family."