Final answer:
The obligation to provide tax return copies to Sean or Madison Williams depends on their engagement contract with Aschli and professional confidentiality rules. Without knowing the specifics of their arrangement, it is not possible to determine whether Aschli must provide documents to one or both parties.
Step-by-step explanation:
The question pertains to an accountant's ethical obligation of client confidentiality under professional standards such as those outlined by bodies like the American Institute of CPAs (AICPA). Unless there are specific agreements or legal requirements dictating otherwise, an accountant is typically obliged to treat all client information as confidential. In the case mentioned, Aschli's obligation to provide copies of previously filed tax returns and supporting schedules depends on who the client is, and who engaged her services. If Sean and Madison Williams jointly engaged Aschli for her services and there is no express prohibition against sharing their information with each other, she might be obligated to provide copies to both Sean and Madison Williams. In contrast, if the accountant was engaged separately by Sean or Madison, she can only provide the documents to the person who engaged her services, unless explicit permission is already meted out by both parties. Therefore, without additional information regarding the engagement contract or the nature of the accountant-client relationship, it is not possible to determine precisely who Aschli is obligated to provide copies to. It is important for Aschli to ensure that she complies with the applicable rules of confidentiality and privacy in her jurisdiction.