Previously, those who downloaded more than 250GB were sent a warning, threatening them with service suspension if they persisted in breaking their download limit.
Research from Sandvine Corp. shows that only 1.5 percent of the U.S. Internet users download more than 250GB per month, and only 1 percent download more than 300GB.
ISPs say they need to find a way to deter heavy downloaders since they can degrade service for other users on the network.
Comcast's Xfinity TV app for Xbox 360 has brought up some questions however, as the video streaming app does not count toward the monthly limit. Rival Netflix, however, is subject to the monthly download limit, but Comcast rejects claims that it is favoring its own product over Netflix, since Xfinity TV content is not provided through the Internet but from Comcast's own equipment.
Video streaming from Xfinity TV's website does still count toward the monthly data cap.