When you're promised a "rate lock" from your lender, it means that you are guaranteed to get a certain interest rate over a determined period while you work on your application process. This prevents you from going through your whole application process and discovering at the end that the interest rate has gotten higher.
Rate lock periods can be various lengths of time, between 15 to 60 days, with the longer spans usually costing more. You can get a longer period for your lock, but in choosing this option, will likely have a higher rate than you would have with a shorter rate lock period
There are other ways to get a reduced rate, besides opting for a shorter rate lock period. A larger down payment will get you a better interest rate, since you'll have more equity from the beginning. You could choose to pay points to improve your rate over the loan term, meaning you pay more initially. To a lot of people, this makes sense and is a good deal..
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