Yes, you will usually need to change or at least clean the filter of a cordless vacuum, but this will vary from vacuum to vacuum. Some cordless vacuums have a filter that can be removed and rinsed at will. Other cordless vacuums have filters that need to be removed and changed on a regular basis. Regardless of the filter type, you can expect to have to do some mild maintenance to ensure a long lifespan of your cordless vacuum.