This calculator models a Help to Buy equity loan — the UK government scheme that lent first-time buyers up to 20% (40% in London) of a new-build property's value, interest-free for the first five years. It projects how your loan balance changes as your property value grows, since the amount you owe is always a percentage of the current value rather than a fixed sum, then shows how interest builds from year six onwards and what repayment could look like depending on when and how you plan to pay it off — whether that's a set year, alongside your main Mortgage, or funded from savings or an ISA. If you're still saving towards a deposit rather than repaying an existing Help to Buy loan, the Lifetime ISA calculator covers the 25% government bonus available to first-time buyers.