We plan to refinance our adjustable-rate mortgage before it goes up in March. Will we get a larger deduction if we take out additional money, and incur PMI (private mortgage insurance) payments, in order to pay some credit cards? Q. Will the PMI be deductible, too? To make sure that you're getting the best mortgage rate available in the market, it is important that you also obtain all information on important costs involved. Getting the best mortgage rate is knowing how much of a down payment you can afford. Aside from that, getting the best mortgage rate is knowing what is the interest rate of your loan.