UK Mortgage & Stamp Duty Calculator

LTV is the size of your mortgage as a percentage of the property's price (or valuation, if remortgaging). UK lenders price mortgages off LTV bands - typically 60%, 75%, 80%, 85%, 90%, 95%. Each step up usually means a slightly higher rate because the lender's risk is greater. A 75% LTV mortgage will normally have a cheaper headline rate than a 90% LTV one on the same property.

Stamp duty is a tax on property purchases, charged in bands. England and Northern Ireland use SDLT (0% to £125,000, then 2%, 5%, 10% and 12% on portions above). Scotland uses LBTT (0% to £145,000, then up to 12%). Wales uses LTT (0% to £225,000, then up to 12%). First-time buyer relief raises the zero-rate threshold in England/NI to £300,000 and in Scotland to £175,000. Additional or second properties pay a surcharge on top - 5% in England/NI, 8% in Scotland. Full breakdown in our stamp duty guide.

A first-time buyer is someone who has never owned a residential property anywhere in the world - including inherited or jointly-owned property. In England and Northern Ireland the relief means no SDLT on the first £300,000 (property must be £500,000 or less). In Scotland LBTT relief raises your zero-rate threshold to £175,000. Wales doesn't offer specific FTB relief because the standard LTT zero-rate threshold (£225,000) is already higher.

Most UK fixed-rate mortgages let you overpay up to 10% of the outstanding balance per year without an early-repayment charge (ERC). Tracker and variable-rate mortgages often have no overpayment limit at all. Above the 10% ceiling, lenders typically charge 1-5% of the overpaid amount during the fix period. Always check your specific mortgage offer document or call your lender before making a large overpayment.

Most UK lenders let you lock in a new mortgage rate up to six months before your current fix ends. Mortgage offers are typically valid for 3 to 6 months, so it's worth starting 4-6 months before your fix expiry to compare deals without rate anxiety. If rates have fallen since you took out the current deal, leaving it until the fix ends can mean rolling onto the lender's standard variable rate (SVR) for a few weeks - usually 3-5 percentage points higher than a fixed deal.

Repayment is the default for UK residential mortgages: each monthly payment covers both interest and a chunk of the capital, so the balance falls to zero by the end of the term. Interest-only keeps the balance flat - you only pay the interest each month, and you must repay the full capital at the end (usually from a separate investment, sale of the property, or by switching to repayment later). Interest-only is most common on buy-to-let mortgages. Residential IO mortgages exist but lenders require a credible repayment strategy.