When you are offered a "rate lock" from the lender, it means that you are guaranteed to keep a certain 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 be various lengths of time, anywhere from 15 to 60 days, with the longer period typically costing more. You can get a longer period for your lock, but in choosing this option, will most likely have a higher rate than you would with a shorter span of time
In addition to choosing the shorter rate lock period, there are several ways you can attain the lowest rate. A bigger down payment will get you a better interest rate, because you will have a good deal of equity from the beginning. You can pay points to improve your interest rate for the loan term, meaning you pay more up front. One strategy that is a good option for some is to pay points to bring the rate down over the term of the loan. You pay more initially, but you'll save money, especially if you keep the loan for a long time.
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