Lock in Your Interest Rate for 150 Days! Chances are, you have heard this line before. But what you need to know is that if you are going to lock in a rate for that long, you can be sure the lender has added a cushion to that rate so that if rates go up, they don’t lose any money. When you are shopping for a mortgage, you need to compare many things, not just rates. Companies that lock your rate for long periods of time state they can safeguard you from volatility of interest rates while you are shopping for a home. Then they comfort you by adding that you can float down to a lower rate if rates reduce. In order for lenders to guarantee rates for a long length of time, they must be hedging the rate or they would lose money. I have seen some mortgage companies that will guarantee a rate for up to 5 months! The longer you lock into a rate, there is going to be a cost associated with it. Be on the lookout when shopping for your next mortgage!