Changing your furnaces filter is the quickest and easiest way to maximize the efficiency of your heating system and help purify your home's air. 

Typically you should change your basic fiberglass filter every 1-2 months, and paper filters every 4 months to a year. You should also clean it more frequently if you have pets in your home if anyone smokes. Also if you are running your furnace more often, especially in colder months, you should check the filter more often and change when you notice a dust buildup.