When you're promised a "rate lock" from the lender, it means that you are guaranteed to keep a particular interest rate over a determined period while you work on the application process. This ensures that your interest rate cannot go up as you are working through the application process.
Although there are various lengths of rate lock periods (from 15 to 60 days), the longer ones are usually more expensive. You can get a longer period for your lock, but in doing so, will most likely have a higher rate than you would have with a shorter span of time
In addition to choosing the shorter rate lock period, there are other ways you are able to attain the best rate. A larger down payment will give you a lower interest rate, because you'll have more equity from the beginning. You can pay points to lower your interest rate over the life of the loan, meaning you pay more up front. For many people, this makes sense and is a good deal..
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