What a house actually costs.

The stamp duty surcharge applies to the whole purchase price if any buyer will own another residential property at the end of completion day — not a share of it, and regardless of whose name is on the mortgage or the title. First-time buyer relief needs every buyer to qualify, so one partner having owned a home before removes it for both buyers, even if the other has never owned anywhere. For a £350,000 purchase: £2,500 if both buyers are first-time buyers, £25,000 if one partner already owns a home and keeps it — a £22,500 difference on the same purchase price. If the buyers are married or in a civil partnership, a partner's property counts against the purchase even when only the other partner's name goes on the title.

Two things, separately. It shrinks the loan directly — £17,500 more deposit on a £350,000 property is £17,500 less borrowed, repaid over the mortgage term regardless of rate. It also determines which loan-to-value (LTV) band applies, and mortgage rates step down as LTV drops — this tool's representative rates go from 5.5% at 90-95% LTV down to 4.5% at 60% LTV or below. The rate no longer improves below 60% LTV (a 40% deposit on a typical purchase), so beyond that point only the smaller loan continues reducing the interest total, not the rate.

Overpaying returns exactly the mortgage's interest rate on the amount overpaid, for as long as the loan is outstanding, with no risk of loss. Investing (a pension, ISA or otherwise) has no guaranteed return — it depends on what happens to the investment. Overpaying stops mattering once the mortgage clears; investing does not. The "interest saved" figure from overpaying already accounts for the extra money paid in, because every pound of overpayment is principal that would otherwise be repaid later anyway — what it does not account for is what that same money could have earned if invested elsewhere instead.

Yes, as a separate selection — pick the country at the top of the form. England and Northern Ireland use Stamp Duty Land Tax (SDLT); Scotland uses Land and Buildings Transaction Tax (LBTT), with its own bands and an Additional Dwelling Supplement instead of a surcharge; Wales uses Land Transaction Tax (LTT), which has no first-time buyer relief at all — a first-time buyer in Wales pays the same LTT as anyone else at the same price — and whose higher rates for additional properties use their own separate set of bands rather than a flat percentage added on top of the standard rates. None of these figures, for any of the three, are verified or guaranteed to be accurate or current — rates and bands change at each government's own Budget. Confirm against HMRC, Revenue Scotland or the Welsh Revenue Authority, as applicable, before relying on any of them for a real transaction.

To produce one comparable number per deposit size. UK mortgage rates are typically fixed for an initial period — commonly 2, 5, or occasionally 10 years — then change at remortgage, not fixed for the full term. The total-interest and rate-saving figures in the deposit table show how much interest would be paid if today's rate applied for the entire term, which it will not. They compare deposit sizes against each other under one consistent assumption, rather than forecasting an actual amount that will be paid.

By loan-to-value (LTV) — the percentage of the property price being borrowed, rather than covered by deposit. Lenders generally price mortgages in LTV bands, with lower rates in lower-LTV bands. This tool's default rate table (in "Mortgage rate by deposit") is an indicative average for each band, not a live feed of lender rates, and every figure in it can be edited to match a real quote.