UK 100% mortgages provide the homebuyer with the entire amount of capital that they need in order to purchase the property. If you wanted to buy a cottage with an asking price of £120,000 then 100% mortgages would provide you with £120,000. 100% buyers are often useful to people like first time buyers who have little capital behind them, but they do come with higher interest rates. You may be legally obliged to stay with the lender for the term of your mortgage and if house prices fall then you could find yourself in negative equity. It is also likely that with a 100% mortgage that you will need to pay out for a mortgage indemnity guarantee policy.