Getting a Low Interest Rate
Freezing the Rate
When you're promised a "rate lock" from the lender, it means that you are guaranteed to keep a set interest rate over a determined period while you work on the application process. This protects you from going through your whole application process and finding out at the end that the interest rate has gotten higher.
Rate lock periods can vary in length, between 15 to 60 days, with the longer spans generally costing more. You can get a longer period for your lock, but in choosing this option, will probably have a higher rate than you would have with a shorter rate lock period
Other Interest Saving Strategies
There are more ways to get a reduced rate, besides agreeing to a shorter rate lock period. A bigger down payment will result in a better interest rate, since you're starting out with a good deal of equity. You could choose to pay points to reduce your interest rate for the term of the loan, meaning you pay more initially. One strategy that makes financial sense for many people is to pay points to bring the rate down over the term of the loan. You'll pay more up front, but you'll save money, especially if you don't refinance early.