The federal government's Help to Buy scheme will do little to help single income Australians, fears KR Peters Director Peter Nicolls.

Mr Nicolls has crunched the numbers and says singles will still have a hard time borrowing the amount required to buy a house even with a hefty contribution from the Commonwealth.

Singles will most likely be confined to buying cheaper apartments and townhouses.

Under the scheme, which passed through federal parliament in the last week of November with the support of the Greens, the income limit for single buyers is $90,000 and $120,000 for couples.

Mr Nicolls says based on the income threshold a single person could borrow a maximum of $450,000, while a couple could borrow a maximum of $610,000.

"So if a single income person was to buy a new home for $850,000 and the government puts in 40 per cent or $340,000, the buyer has to fund $510,000. Their maximum loan capacity would be $450,000, so the buyer needs to inject an extra $60,0000 plus stamp duty, legals and bank charges," Mr Nicolls explained.

A couple would also need to inject money into the purchase above the 2 per cent deposit required under the scheme.

"If a couple buy a new home for $850,000, the government puts in 40 per cent or $340,000. The couple also needs a 2 per cent deposit which is $17,000. Their maximum borrowing capacity is $493,000 meaning they need to inject another $17,000 plus stamp duty, legals and bank charges.

"Keep in mind this is based on moderate living expenses and no ongoing commitments. Simply speaking single income buyers will struggle to buy with the scheme. They will struggle to come up with $60,000 plus stamp duty, legals and bank charges."

It will be even harder for singles to buy an existing property. Under the scheme the federal government makes an 'equity contribution' of up to 40 per cent of the cost of  a new build and 30 per cent of an existing property.

There is no date yet announced for when the scheme will start in Victoria as the state government also needs to pass legislation transferring powers to the Commonwealth before the initiative can  take effect.