When you're offered a "rate lock" from your lender, it means that you are guaranteed to keep a specific interest rate for a certain number of days while you work on your application process. This keeps you from working through your whole application process and discovering at the end that the interest rate has risen higher.
Rate lock periods can vary in length, anywhere from fifteen to sixty days, with the longer period generally costing more. A lending institution will agree to hold 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 that of a rate lock of fewer days.
In addition to choosing a shorter lock period, there are several ways you can score the best rate. The more the down payment, the smaller the interest rate will be, as you will be entering the loan with more equity. You could opt to pay points to improve your 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 reduce the interest rate over the life of the loan. You'll pay more up front, but you'll come out ahead, especially if you don't refinance early.
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