Melbourne's Liberal Lord Mayor has questioned a plan to tax the foreign owners of vacant properties, saying a similar scheme has been a challenge in Canada.

Unveiling the federal budget last night, treasurer Scott Morrison revealed foreign owners will be charged $5,000 if their property is empty for more than six months.

Melbourne Lord Mayor Robert Doyle said the mayor of Vancouver has had difficulty enforcing a similar tax in his city.

He also questioned the decision to target foreign owners.

"If it's an empty apartment and we think it should be part of the housing stock, why not anybody?" he said on ABC Radio Melbourne.

"[Mayor] Gregor Robertson is trying to the same thing in Vancouver and he's finding it incredibly difficult to actually identify which are the apartment blocks that are empty."

The federal measure follows a similar move in Victoria, where the Andrews Government will tax 1 per cent of a property's capital improvement value if it is empty for six months.

The Victorian measure will apply to all residential properties, not just those that are foreign-owned.

Measuring water and electricity usage is a common way to gauge if a house is occupied, but Cr Doyle said that was easy to fudge.

"You can actually have electricity turned on or water turned on automatically if you wanted to demonstrate consumption," he said.

"Those things are quite easy to do at a distance. You can run your utilities so there's some usage shown. You spend a couple of hundred dollars to save you $5,000.

"I think it [the tax] is quite a good idea, I just don't know how they're going to do it."

Help, not handouts, for first home buyers: Morrison

Slugging vacant properties is designed to ease the demand for homes, as house prices and rents skyrocket in major cities.

Mr Morrison said his budget had done its bit to address housing affordability, particularly for first home buyers.

"We're not giving people handouts to buy homes, what we're doing is we're helping them accelerate their savings," he said.

"In Melbourne itself, we're releasing the Commonwealth land at Maribyrnong. That'll support 6,000 new homes.

"We're building the duplication of the Waurn Ponds to Melbourne rail line, which means Geelong, and affordable housing in Geelong, will be better connected to the major city of Melbourne.

"We're incentivising the State Government of Victoria to free up its planning and zoning controls, and build more homes, we've got tax incentives to build more affordable housing."

No quick fix

From July 1, prospective buyers will be able to make voluntary contributions of up to $15,000 a year and $30,000 in total to their superannuation account, and then withdraw it to purchase their first property.

Commsec's chief economist Craig James said the the scheme was a smart measure, but it was unlikely to have an impact on the market in the short-term.

"If we're looking for a quick fix for housing affordability, particularly in terms of Sydney and Melbourne, well, it's not going to be here," Mr James said.

"You're not going to find that in terms of the budget document."

Joseph Walton, of the Real Estate Institute of Victoria, said the salary sacrifice scheme did not go far enough.

"In metropolitan Melbourne, we've got a median house price of $870,000," he said.

"Thirty-thousand dollars is going to do very little in terms of saving up that 10 per cent deposit."

Mr Walton said the first home owner grant should be extended to established homes in Melbourne.

"[First home buyers are] the market participants that are going missing at the moment and they're the ones who need to be given the opportunity to participate," he said.