How often you need to change your filter depends upon which type of filter you are using.

Here are some basic guidelines on when to change your filter:

Traditional Fiberglass or Polyester:	Monthly
Washable/Reusable:	Washed out monthly and reused
Ordinary Flat or Pleated:	Every 2 - 3 months
Deep Pleated:	Once or twice a year
Pleated, Permanently Charged Electrostatic:	Every 2 - 3 months
Electronic Air Cleaner:	Cleaned regularly (once a month)

It is also important that your air filter fit your air return properly. If the air filter fits loosely into the air return, then the air flow will move around the filter and not through the filter. An improper fit is like not having an air filter at all! A suggestion for filters that are loose fitting is to use tape around the edges to secure it properly.