A rate "lock" or "commitment" is a lender's promise to set a particular interest rate and a certain number of points for you for a certain period during your application process. This ensures that your interest rate cannot get higher as you are working through the application process.
Rate lock periods can vary in length, anywhere from 15 to 60 days, with the longer spans typically costing more. You can get a longer period for your lock, but in choosing this option, will probably have a higher interest rate than you would with a shorter span of time
There are other ways to get a lower rate, besides choosing a shorter rate lock period. A larger down payment will result in a lower interest rate, since you'll have a good deal of equity from the beginning. You can pay points to reduce your 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 improve the interest rate over the term of the loan. You will pay more initially, but you will come out ahead, especially if you keep the loan for the full term.
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