A rate "lock" or "commitment" is a promise from the lender to hold a specific interest rate and a certain number of points for you for a specified period during your application process. This ensures that your interest rate won't grow while you are working through the application process.
While there are several lengths of rate lock periods (from 15 to 60 days), the extended ones are usually more expensive. You can get a longer period for your lock, but in making this choice, will most likely have a higher interest rate than you would have with a shorter period
In addition to going with the shorter lock period, there are several ways you are able to get the lowest rate. A bigger down payment will give you a reduced interest rate, because you'll have a good amount of equity at the start. You can pay points to bring down your interest rate over the loan term, meaning you pay more up front. One strategy that makes financial sense for many people is to pay points to reduce the rate over the life of the loan. You'll pay more initially, but you will save money in the long run.
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