Cost of self cert mortgages are slightly higher than conventional or mainstream mortgage as more risks for lenders are represented and interest rates then commensurate with risk involved. Interest rates are 0.5 % to 1.5 % higher than original or mainstream rates. These rates used to be much higher than present ones. Because of increasing number of borrower having varied income and arrival of more lenders in this field has enhanced competition and has created more favourable atmosphere for borrower. Whatever interest rates are, lender has to ensure that money will be paid back. This is aspect of affordability over which scrutiny of lender revolves and is a decisive factor in giving loan.