You may have heard of the term ‘qualifying rate’. There is some confusion about what this means and how it affects you as a borrower. The qualifying rate – typically defined as the Annual Percentage Rate – will affect whether or not your mortgage application will be approved and at what interest rate.The lower your credit rating, the higher your interest rate is likely to be.f you have a smaller deposit, the lower your interest rate will be because this provides less security for the lender in case you default on your repayments.