When you are promised a "rate lock" from a lender, it means that you are guaranteed to keep a set interest rate over a certain number of days while you work on the application process. This prevents you from going through your entire application process and discovering at the end that your interest rate has gone up.
Rate lock periods can vary in length, between fifteen to sixty days, with the longer period typically costing more. The lending institution may agree to freeze an interest rate and points for a longer period, like sixty days, but in exchange, the rate (and sometimes points) will be more than that of a rate lock of a shorter period.
In addition to opting for a shorter rate lock period, there are more ways you can attain the best rate. A bigger down payment will give you a lower interest rate, since you'll be starting out with a good deal of equity. You can pay points to reduce your rate over the loan term, meaning you pay more initially. For a lot of people, this makes financial sense..
Do you have a question regarding a mortgage program?