When you're offered a "rate lock" from your lender, it means that you are guaranteed to get a specific interest rate over a determined period while you work on the application process. This means your interest rate can't get higher during the application process.
Rate lock periods can be various lengths of time, between fifteen to sixty days, with the longer period generally costing more. A lender may agree to freeze an interest rate and points for a longer span of time, say 60 days, but in exchange, the rate (and sometimes points) will be higher than that of a rate lock of fewer days.
There are more ways to get a low rate, in addition to going with a shorter rate lock period. A larger down payment will result in a lower interest rate, because you will have more equity at the start. You can pay points to lower your interest rate over the loan term, meaning you pay more initially. For many people, this is a good option..
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