Option ARM vs. Fixed Rate MortgageA fixed rate mortgage has the same payment for the entire termof the loan. The Option ARM uses a low initial rate to calculateyour initial minimum monthly payment. Although the interest ratewill increase after 1 to 3 months, your low payment will remainfixed for the entire year. This can produce a much lower monthlypayment than a traditional fixed rate mortgage, or even anadjustable rate mortgage (ARM).