If you rent a dedicated server in US and make money, are you subject to US tax?
This is something I've been trying to figure out... if you rent a server in the US and you only sell digital goods (majority of clients are US-based) through PayPal, are you technically "doing business" in the United States?
If not, then at what point would it be considered as doing business in the US?
Usually when you sell downloadable goods - not a product that you can touch / feel, etc, then sales tax is not warranted. If you were to mail that customer a CD and you were incorporated in the same state as your customer, chances are you would have to charge tax.
But the best person to ask is your account or attorney. Your relationship with them will help them to make that determination.