A rate "lock" or "commitment" is a lender's promise to set a specific interest rate and a specific number of points for you for a specified period while your application is processed. 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 spans usually costing more. The lending institution will agree to hold an interest rate and points for a longer period, such as 60 days, but in exchange, the rate (and sometimes points) will be higher than with a rate lock of a shorter period.
There are more ways to get a reduced rate, in addition to going with a shorter rate lock period. The more the down payment, the better the rate will be, since you will be entering the loan with more equity. You can pay points to lower 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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