 Historically, investment-backed mortgages offered various tax advantages over repayment mortgages, although this is no longer the case in the UK.Investment-backed mortgages are seen as higher risk as they are dependent on the investment making sufficient return to clear the debt.Until recently it was not uncommon for interest only mortgages to be arranged without a repayment vehicle, with the borrower gambling that the property market will rise sufficiently for the loan to be repaid by trading down at retirement (or when rent on the property and inflation combine to surpass the interest rate).