A: This depends on how long you keep the mortgage. You can calculate the breakeven period quickly by dividing the cost of buying down the rate by the monthly savings. The longer you stay in the house (without refinancing again), the more it makes sense to buy down the rate. Keep in mind that, on average, people refinance every 5.5 years and sell after 10 years. You may also consider rolling the points (the price you pay for the lower rate) into the loan so you do not have to come up with that money out of pocket. Read: Interest Rate: Buying Down Your Mortgage Rate.