A rate "lock" or "commitment" is a lender's promise to freeze a specific interest rate and a particular number of points for you for a specified period during your application process. This keeps you from going through your whole application process and finding out at the end that the interest rate has risen higher.
Rate lock periods can vary in length, between 15 to 60 days, with the longer ones usually costing more. You can get a longer period for your lock, but in doing so, will probably have a higher interest rate than you would with a shorter span of time
In addition to opting for the shorter lock period, there are more ways you can get the best rate. A larger down payment will result in a better interest rate, because you'll be starting out with more equity. You might opt to pay points to reduce your interest rate over the loan term, meaning you pay more initially. To a lot of people, this is a good option..
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