Brian, a US citizen and a resident of California, signed a contract with an Italian clothing company to promote their fall/winter clothing line. A photographer, engaged by the Italian clothing company, will take photos of Brian modeling the outerwear for the clothing company for use in their advertising campaign (e.g., print and social media). The photos will be taken in Milan, Italy and the advertising campaign will be worldwide. Brian will be paid $50,000. The Italian clothing company has indicated that they will withhold the maximum amount required by the US-Italy tax treaty unless Brian can properly document his US residency. Determine the steps that must be taken to document Brians residency and how much tax will be saved.