Payments. Most borrowers now pay the PMI premium as part of the monthly mortgage payment. The PMI rate is figured as a percentage, usually around 1 to 2 percent, of the outstanding principal amount of the loan, divided into twelve monthly payments.efaults. At one time, mortgages carried a minimum down payment, usually 20 percent of the purchase price. The down payment was meant to ensure that the buyer would honor the loan commitment, as defaulting would mean the loss of a large investment.