The Scottish government's Help to Buy scheme is to be extended for another two years from April 2019.
The scheme helps people to buy new-build homes without the need for large deposits.
A total of £100m will be invested over two years, helping up to 4,000 households to purchase a new home.
But Scottish Labour's housing spokeswoman Pauline McNeill called for an urgent review of the scheme to establish if it is "fit for purpose".
She said householders with incomes of more than £100,000 were getting help with a new home deposit and efforts must be directed to low income households.
'A fairer Scotland'
Since 2013, the scheme has helped more than 12,000 households buy a new home, with Housing Minister Kevin Stewart saying it had also supported about 9,000 jobs.
Mr Stewart added: "A third of the annual £50m budget - £18m - will be reserved for sales from SME builders, who were particularly affected by the drop in development finance after the financial crisis.
"We know house builders still see Scotland as a place to continue to develop and invest, with the latest figures showing new house completions grew by 5% over the last year.
"Housing is about more than bricks and mortar - we want to provide safe, warm homes, help create a fairer Scotland, and preserve a diverse and more resilient construction sector."
Nicola Barclay, chief executive of Homes for Scotland said the additional funding would help provide the certainty house building companies need to invest in and open up new sites and expand the number of homes available to new purchasers.
And she said it would also ease pressure in other parts of the housing market as people move into home ownership from socially rented homes and come off council house waiting lists.
The Scottish Conservatives back Help to Buy, with the UK government operating a similar scheme.