When you're offered a "rate lock" from your lender, it means that you are guaranteed to get a particular interest rate for a certain number of days while you work on your application process. This prevents you from working through your entire application process and discovering at the end that your interest rate has gotten higher.
Rate lock periods can be various lengths of time, between fifteen to sixty days, with the longer spans typically costing more. A lender may agree to freeze an interest rate and points for a longer span of time, such as 60 days, but in exchange, the rate (and sometimes points) will be more than with a rate lock of fewer days.
In addition to going with a shorter lock period, there are several ways you may be able to attain the best rate. A bigger down payment will result in a better interest rate, since you'll have more equity at the start. You may opt to pay points to reduce your interest rate over the term of the loan, meaning you pay more up front. One strategy that is a good option for many people is to pay points to improve the rate over the life of the loan. You'll pay more initially, but you will save money in the long run.
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