When someone is appointed as power of attorney, he is an agent acting on behalf of another person, and his duties vary depending on the type of powers that the principal grants, according to Legal Zoom. Those duties include making donations or working with the IRS on behalf of the principal.
The agent on a power of attorney has a legal responsibility to the principal. He must act in the best interests of the principal and not his own. He should keep accurate records of all the duties he's asked to perform on behalf of the principal, including an accounting of activities if the principal or a court asks for one, according to Legal Zoom.
When the principal passes away, the power of attorney immediately terminates. The principal can revoke the power of attorney at any time, and an agent can resign from his duties by notifying the principal in writing of his wish to resign and the reason why he's resigning. Most power of attorney duties begin once the document has been signed, but some don't begin until the principal is no longer able to make decisions on his own, according to Legal Zoom. The power of attorney states when the document becomes valid and enforceable.