The maximum purchase price you can afford with Help to Buy is £600,000. For the first five years after you buy your Help to Buy a home, you are interest-free. To buy your new home under Help to Buy, you are required to pay a deposit. The deposit has to be at least 5% of the property’s purchase price. The government’s equity loan covers up to 20% of the cost. While the Help to Buy Mortgage can cover the remaining balance.