Comcast will start charging extra when the company's customers go over the 300GB monthly data limit. That limit, however, is very high, meaning that not many Internet users use that much data in a month.

Comcast said Thursday that it will test charging $10 for every 50 gigabytes over that limit.

Comcast has previously limited use to 250GB per month, but hasn't charged those who exceed that limit.

Comcast's Xfinity TV service is excluded from the data cap when it's viewed on its app on the Xbox game console. Video from XfinityTV.com does count toward the limit.