A power of attorney is a written document in which one person, known as the principal, designates another person, known as the agent or attorney-in-fact, the authority to act on his behalf. Using a statutory durable power of attorney is no different than using any other kind of POA. The terms "statutory" and "durable" refer to its contents. A statutory POA is a basic form, available from legal supply stores and on the Internet. It conforms to your state’s laws without enumerating the laws in detail. When a statutory POA is durable, it includes language indicating that the agent’s powers remain in effect when and if the principal is no longer mentally competent.
Make several copies of the POA. Because it’s durable, you won’t want to risk losing or misplacing the original. If the principal becomes mentally incapacitated, he cannot sign a new one; a guardianship or conservatorship proceeding would become necessary for you to continue overseeing his affairs. The agent can also sign more than one original to safeguard against this.
Present a copy of the POA to any entity or third party with whom you must deal on behalf of the principal. Explain that you’re acting as attorney-in-fact on his behalf. Some institutions, such as banks, might ask for a period of time to allow their legal counsel to review the document. The third party will probably want to keep a copy of the POA for its records.
Sign an additional affidavit, attesting that you are acting on the authority of the principal, if the third party requires it. Some institutions require this “double” proof that you have permission to act on behalf of the principal. If anyone requests that you sign an affidavit, you’re obligated to do so.
Sign all documents on behalf of the principal with his name first, your name second, and finish with a notation that you’re operating under a POA. For example, sign “John Jones, by Sam Jones as his attorney-in-fact,” or “John Jones, by Sam Jones, power of attorney.” This makes it clear that you’re not entering into the transaction personally.
Ask for a copy of anything you sign so you have a record of it. If any of your actions come under scrutiny, you’ll have a complete journal, with documentation, of everything you’ve done on behalf of the principal. Keep everything in a binder or a filing cabinet, with notes identifying the institution with whom you dealt, the date you acted and why you did what you did.