A rate "lock" or "commitment" is a lender's promise to lock in a particular interest rate and a certain number of points for you for a specified period during your application process. This means your interest rate won't get higher while you are going through the application process.
Rate lock periods can be various lengths of time, between 15 to 60 days, with the longer spans generally costing more. A lender may agree to hold an interest rate and points for a longer period, such as sixty days, but in exchange, the rate (and sometimes points) will be higher than that of a rate lock of fewer days.
There are more ways to get a low rate, besides agreeing to a shorter rate lock period. The bigger the down payment, the lower your interest rate will be, since you will have more equity from the beginning. You can pay points to lower your interest rate for the loan term, meaning you pay more up front. One strategy that is a good option for many people is to pay points to improve the interest 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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