When you're looking to start webhosting, you are essentially, operating your own company. You will need to look into your local (state, federal, government, etc) requirements for doing so. Since these very incredibly by locale, this really isn't something that can be answered here.
In the U.S., all that is required to run your business is a social security #, for tax reporting purposes.
However, each individual state has it's own rules regarding this, and each individual city, then county have THEIR own as well.
Since you will be taking income from the hosting business (hopefully), this will need to be reported back to your local government however they require you to do it.
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Welll that depend on the rules of business that governement has chalked out depending on geographical locations. Every countries rules for runing and selling a business is different. You need to follow those rules for selling your business.