When you're offered a "rate lock" from a lender, it means that you are guaranteed to get a set interest rate over a determined period while you work on the application process. This protects you from working through your entire application process and discovering at the end that the interest rate has risen higher.
Rate lock periods can vary in length, between 15 to 60 days, with the longer ones generally costing more. A 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 more than with a rate lock of fewer days.
There are more ways to get a lower rate, besides choosing a shorter rate lock period. A bigger down payment will result in a reduced interest rate, since you're starting out with a good deal of equity. You could choose to pay points to bring down your interest rate for the term of the loan, meaning you pay more up front. One strategy that is a good option for some is to pay points to reduce the interest rate over the term of the loan. You are paying more up front, but you will save money, especially if you don't refinance early.
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