When you're offered a "rate lock" from the lender, it means that you are guaranteed to keep a particular interest rate for a determined period for the application process. This means your interest rate can't rise during the application process.
Rate lock periods can be various lengths of time, between 15 to 60 days, with the longer period usually costing more. You can get a longer period for your lock, but in choosing this option, will likely have a higher interest rate than you would with a shorter period
There are other ways to get a good rate, in addition to opting for a shorter rate lock period. The bigger down payment you can pay, the smaller your rate will be, because you will be entering the loan with more equity. You can pay points to reduce your interest rate for the term of the loan, meaning you pay more initially. For many people, this makes financial sense..
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