The first mortgage rates on offer under the latest phase of the Government's Help to Buy scheme have been described by lenders as "fair and competitive."
The latest phase will see 15% of a property's value guaranteed by taxpayers, to help homebuyers obtain mortgages worth up to 95% of a property's value.
RBS and its Natwest subsidiary said they would be offering two and five-year fixed rate deals at 4.99% and 5.49% interest rates respectively with no fee. The brands expect a rush of interest - signing up 25,500 first and next time buyers over three years.
The banks confirmed 740 of their branches would extend opening hours for two weeks to cope with expected demand but Lloyd Cochrane - their head of mortgages - told Sky News there would be no reckless lending with potential customers facing tough affordability checks.
Lenders can start offering the mortgages from today, and they will be guaranteed by the Government from January 2014.
Halifax - owned by Lloyds Banking Group - later confirmed its offering: A two-year fixed rate at 5.19% with a £995 product fee and said customers would be able to apply for the mortgages from Friday.
HSBC said it would be taking part later in the year, making it the first major player with no taxpayer support to sign up.
Virgin Money and the start-up Aldermore Bank will join from January while Barclays and Santander UK are still considering whether to participate.
The scheme had initially not been expected to start until the new year but was brought forward by three months.
It will offer £12bn in mortgage guarantees over three years and some estimates suggest 180,000 loans could be taken out under the initiative.