[sprite]

Wouldn't substantial presence test determine tax payer status? I've been paying US income tax the past few years without even being there on a visa, simply by meeting substantial presence test while on visa waiver and not claiming a closer relation to any other country. [I travel a lot and spend more time in the US than anywhere else [roughly 5 months out of the year], but don't technically live anywhere]

[beagle3]

That requires tax payer obligation. However "american taxpayer" is a well defined status reflected in laws and regulation which you may or may not have, even if you are paying US taxes regularly.

If you do have "american taxpayer" status, banks outside the US (essentially all of them these days) will refuse to let you do anything other than keep a checking and saving account, and brokers will refuse to do business with you, thanks to SEC regulations that say that only SEC regulated brokers and banks can handle securities on behalf of US taxpayers.