The government has made more than £200 million from the Help to Buy scheme since it was launched two-and-a-half-years ago.
According to property firm Hometrack, rising house prices in many areas of England have seen the values of homes bought through the scheme soar by more than £1 billion.
The Help to Buy scheme was launched in April 2013. It gives buyers an interest-free loan for five years in for a percentage of the property - usually 20% of the mortgage. When the house is sold, the owner returns the value of that percentage to the Treasury.
The 20% stake is a maximum, but assuming every buyer took the percentage, the government will have earned £213 million up to the end of September 2015. Because the value returned to the government depends entirely on house prices, some areas have seen the government lose some money. In Wyre, Rossendale and Hartlepool, the Treasury lost between £40,000 and £100,000. But the biggest earners were in Milton Keynes, County Bedfordshire and Aylesbury Vale, where the Treasury made a combined £17.2m.
Hometrack's research director Richard Donnell described the profit made on the scheme as "incidental", pointing out that "clearly the government is not doing this as a money-making scheme, it is doing it to stimulate the market."
However, Mr Donnell also raised concerns over the impact the new starter home scheme could have on Help to Buy. The new scheme will see new homes sold for 20% less than their market value. Mr Donnell said: "There is some concern for all of the people who have done well from their Help to Buy unit - the starter home has the potential to distort the market a bit at the local level."