The second part of the Help to Buy scheme will be available from this week after the Government brought forward the launch date by three months.
The mortgage guarantee scheme, which allows prospective homeowners in England to take out 95% mortgages, was due to start in January 2014 but people will be able to start applying for the new mortgage guarantee from this week.
The mortgages - backed by the Government - will help people buy new or existing homes worth up to £600,000 with a 5% deposit.
The Government then guarantees the next 15% of the loan for a fee with the homeowner expected to find a 75% LTV mortgage.
The scheme will initially be available for three years up to January 2017.
The Prime Minister has been forced to defend the scheme after critics, including business secretary Vince Cable, warned it could spark a fresh housing bubble.
On Friday, a statement, released after a meeting of the Financial Policy Committee, set out central bank plans to ‘closely monitor' the housing market and intervene if it feels property prices are overheating.
Speaking on the BBC's Andrew Marr Show, David Cameron said: "The Bank of England said expressly, there isn't a bubble. The housing market is recovering, but from a low base.
"As Prime Minister, I'm not going to stand back while people's aspirations to get on the housing ladder, to own their own flat, to own their own home, are being trashed."
Last week, the Bank of England moved to calm fears by saying it would step in if a bubble emerged in the housing market.
The first phase of the Help to Buy scheme launched in Scotland this morning.
The equity loan scheme has generated more than 12,500 sales in England since its launch in April and the Scottish government was keen to launch an equivalent.
