Treasurer Scott Morrison has dismissed as "out of date" an internal Reserve Bank memo which expressed concerns about negative gearing and capital gains tax concessions.

The 2014 memo, released under Freedom of Information laws, said any change that discouraged negative gearing might be "a good thing" from a financial stability perspective.

Mr Morrison, speaking to ABC radio on Tuesday, pointed to a recent warning from credit rating agency Moody's that a negative shock to the housing market could derail the economy.

Labor wants to limit negative gearing to new homes and do away with the 50 per cent discount on the capital gains tax.

Mr Morrison said the "reckless" policy threatened to lower the value of established homes and increase rents as investors sought to recover losses.

He insisted the memo was not official RBA advice and didn't apply to the situation in 2016 following measures introduced by the banking regulator.

"Frankly, it's out of date," he said.

Nor was it the RBA's official position.

The memo says negative gearing and capital gains tax rules affect property more significantly than other investments "as it can be purchased with higher leverage than shares".