Advinans only allows persons who are taxable only to Sweden to become customers. To allow customers who are taxable to other countries would involve a cost for Advinans which would ultimately need to be borne by our other customers. That is why we have chosen not to allow it at present.
Taxable means an obligation to pay some type of tax, for example income tax, in a particular country. It is possible to be taxable to several countries but normally it is only to the country where you are primarily resident.
The US has particularly strict rules and if you have any type of close connection to that country such as citizenship, residence permit, own real estate or have had a long-term stay in that country, Advinans recommend that you contact the IRS to determine any potential tax liability to ensure that you are not a so-called US Person.