Problem:

As Pharma Heal Corporation has grown successful, so have Akosua and Isabella. With record sales this past year (thanks to the help of its international business consultant), Isabella realized the substantial income from a variety of sources in several nations. Assume that Isabella is a citizen of Mexico, she resides in the United States, and she owns a beach-front condominium in Monaco that produces substantial income from rental, and that she owns stocks and bond instruments in Switzerland. This, however, has created a headache for her accountant. The accountant is uncertain of Isabella's tax liability. She has asked you, as Isabella's business consultant, to share your views with her by letter on four critical questions:

• To which of these countries will Isabella have to pay income taxes?
• On what specific income will each country be able to impose taxes?
• On what basis will each country be able to impose taxes?
• How would a double taxation treaty between any of these nations possibly change your answer?

Additional Information:

The question is from Finance and it deals with tax liability for income from foreign countries. Isabella is Mexican, working in the US with income from different sources coming in from countries like Monaco, Switzerland, etc. As a business consultant, her Isabella's tax liability needs to be computed.