When you are offered a "rate lock" from your lender, it means that you are guaranteed to keep a specific interest rate over a determined period while you work on your application process. This saves you from going through your entire application process and finding out at the end that your interest rate has risen higher.
Although there can be a choice of rate lock periods (from 15 to 60 days), the longer spans are usually more expensive. A lender may agree to hold an interest rate and points for a longer period, like sixty days, but in exchange, the rate (and sometimes points) will be higher than with a rate lock of fewer days.
In addition to opting for a shorter rate lock period, there are several ways you can get the lowest rate. The more the down payment, the lower the rate will be, as you will have more equity from the beginning. You could choose to pay points to reduce your interest rate for the life of the loan, meaning you pay more initially. One strategy that is a good option for many people is to pay points to reduce the rate over the term of the loan. You are paying more up front, but you'll save money in the long run.
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