When you are offered a "rate lock" from a lender, it means that you are guaranteed to get a set interest rate over a certain number of days for the application process. This ensures that your interest rate won't grow as you are going through the application process.
Rate lock periods can vary in length, anywhere from 15 to 60 days, with the longer ones generally costing more. The lender can agree to freeze an interest rate and points for a longer span of time, such as sixty days, but in exchange, the rate (and sometimes points) will be more than with a rate lock of a shorter period.
In addition to going with a shorter rate lock period, there are several ways you can attain the best rate. The larger the down payment, the better your interest rate will be, as you will be entering the loan with more equity. You might opt to pay points to bring down your interest rate over the life of the loan, meaning you pay more initially. For a lot of people, this makes financial sense..
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