A power of attorney allows a person, referred to as an agent or attorney at law, to act on behalf of another person, the principal. The authority is granted to the agent upon the execution of a power of attorney document that is signed by the principal. Although an agent can make important decisions and perform certain actions for the principal, the agent cannot alter a will, a document consisting of the principal's directions for his estate after his death.
An agent can perform the duties specifically listed in the power of attorney document. The powers can include bank transactions, signing papers for the sale or mortgage of real estate, gift giving and representing the principal in tax matters with the IRS. While the agent may have the authority to arrange for funeral services and purchase a burial plot for the principal prior to her death, he cannot insert or alter burial provisions in the will itself.
A standard power of attorney provides for financial powers, like banking and real estate matters. A power of attorney for health care allows the agent to make medical decisions for the principal if the principal is incapacitated. Unlike a living will, which provides for the wishes of a person in specific medical situations, a health care power of attorney allows the agent to have decision-making authority in unexpected scenarios. A health care agent cannot alter any provisions of a last will.
Both a health care and financial power of attorney can ensure the principal's decisions and wishes about his medical and monetary affairs are upheld even if he can no longer make the decisions himself. However, as the authority ends with the principal's death, his will must reflect his final desires for the distribution of his money and property.
An agent can only make decisions for an incapacitated principal if the executed power of attorney document is durable, meant to withstand the principal's incapacitation. A power of attorney can have a time limit inserted on the document, with the agent's authority ending on the termination date, or only grant authority for a specific situation, like the sale of a particular home. The principal can revoke the agent's authority by executing a revocation document that meets the standards of her state of residence. A will that has been altered by a principal is generally considered invalid for probate, the proceedings used to settle a person's estate.