The traditional answer to that question is when interest rates fall 2 percent below your current mortgage interest rate. However, in recent years some experts have argued that refinancing may be appropriate with a smaller point spread. Some weight is often given to the length of time the owner anticipates holding on to the property. If the owner expects to keep the property for at least three or four years, then refinancing may be worthwhile. While refinancing can involve upfront costs, in many cases it is possible to roll the costs of the refinancing into the new note and still reduce the amount of the monthly payment.