There is more than one type of power of attorney and they are effective as written in the document itself or pursuant to state law.
For example, a financial power of attorney can be effective immediately or it can spring to life when a specific event occurs (i.e. your disability.) Most financial (also called “general durable”) powers of attorney are effectively immediately, so there is no delay in your agent stepping into your shoes when needed.
Another kind of power of attorney is the health care power of attorney. A health care power of attorney is effective only if your doctor states that you cannot provide informed consent for medical care.
A real estate power of attorney is only effective for a particular closing or real estate event; and, a business power of attorney is usually only effective for a specific business transaction. They are used for convenience, not because someone is incapacitated.
If you have minor children, it’s in their best interest for you to have a stand-by guardianship declaration that appoints guardians to care for your children, during your lifetime, if you cannot care for them yourself due to incapacity. You may want such a declaration if you are travelling and leaving your children with friends or relatives. However, you also need to have a permanent declaration.
The guardians you appoint in your will have no authority to act, unless you’re dead, because your will is only effective if you’re dead. You need a general stand-by guardianship declaration to avoid delay and court interference, in having your children placed with the guardians you’ve named in your will.
All of your powers of attorney end at your death. As soon as you die, your power of attorney documents are no longer effective. Your trusted helpers must have authority under another legal document such as a will or trust in order to act after your death.
Be sure to consult with a qualified estate planning attorney to best ensure that your powers of attorney work and are legally valid.