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?

I would say that you are doing business in your country of residence or the country where your business is set up.

The fact that you purchase services from the US and sell to US clients is irrelevant. However, the US clients may be liable to pay import duties on the goods that you sell.

You may be able to get some info from the US tax authority

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.

Thanks for the tips... will catch my accountant out of the office, that way he can't start the clock running on his desk when he picks up the phone. :)

Are you setting up a bank account, merchant account and processor here in the States as well.

Add that into the mix and, please, let us know what your accountant says

Wonder if that will be different that what the IRS says?