When you're offered a "rate lock" from a lender, it means that you are guaranteed to get a certain interest rate over a determined period while you work on the application process. This protects you from working through your whole application process and learning at the end that the interest rate has gone up.
Rate lock periods can vary in length, between fifteen to sixty days, with the longer period generally costing more. The lending institution may agree to freeze an interest rate and points for a longer period, such as sixty days, but in exchange, the rate (and sometimes points) will be higher than with a rate lock of a shorter period.
There are other ways to get a lower rate, in addition to going with a shorter rate lock period. The bigger down payment you pay, the lower your interest rate will be, since you will be starting with more equity. You could choose to pay points to reduce your interest rate for the life of the loan, meaning you pay more up front. One strategy that makes financial sense for some is to pay points to improve the rate over the life of the loan. You are paying more up front, but you will come out ahead in the end.
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