If your earnings come from a corporation like Google (Adsense) or CJ, they will send you a 1099 I think. If the rest of your earnings amount to anything much, you've got to file self-employment income. (like me ) The good news is that I designed and maintain my accountants website, so he files everything for me free of charge!
If you are a US citizen and have made any income from website related activities, you must pay taxes for the income. I keep my website income separate from my personal income. For the website, I list myself as a Sole Proprietership and pay taxes that way. If you are unsure, go see an accountant. The last thing you want is the IRS visiting.
I saw on the simspns how they audit. When they're sorting all of the mail that comes in any packages that land in the box, BAM! Severe Audit. My aunt got audited about 4 years ago, they wanted everything for the past 6 years...woo hoo! guess whos not paying anything this year? This guy, I have 0 profits for my hosting company
I still claimed everything though lol. Just didn't make anything, so I can't pay taxes on no income Stupid advertisement, its expensive lol.