A rate "lock" or "commitment" is a lender's promise to freeze a specific interest rate and a certain number of points for you for a specified period of time while your application is processed. This saves you from getting through your whole application process and discovering at the end that your interest rate has risen higher.
While there may be a choice of rate lock periods (from 15 to 60 days), the extended spans are usually more expensive. 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 rate lock span of time
There are other ways to get a good rate, besides going with a shorter rate lock period. A larger down payment will result in a reduced interest rate, since you are starting out with more equity. You may choose to pay points to bring down your interest rate for the term of the loan, meaning you pay more up front. For many people, this makes financial sense..
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