Mortgage acceleration clause is a clause allowing a lender to demand the entire balance of a loan to be repaid in a lump sum under certain circumstances. The acceleration clause applies if the home is sold, title to the property is changed, the loan is refinanced or the borrower defaults on a scheduled payment. This clause is added to a mortgage loan agreement as a protection to the lender. It is the legal right of a lender to demand the outstanding loan amount. The clause acts as a mortgage agreement demand feature which empowers lenders to demand paying the mortgage if the borrower violates any of the obligations in the mortgage agreement.