A rate "lock" or "commitment" is a lender's promise to hold a certain interest rate and a certain number of points for you for a certain period of time while your application is processed. This prevents you from going through your whole application process and learning at the end that the interest rate has risen higher.
Rate lock periods can be various lengths of time, between 15 to 60 days, with the longer ones typically costing more. You can get a longer period for your lock, but in doing so, will probably have a higher rate than you would have with a shorter period
In addition to choosing the shorter lock period, there are other ways you may be able to get the best rate. A bigger down payment will get you a reduced interest rate, since you will be starting out with more equity. You can pay points to reduce your interest rate for the term of the loan, meaning you pay more initially. To a lot of people, this is a good option..
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