If your father, for example, and his present spouse, have all their income and assets under both their names, it may not seem as if there's any need for a power of attorney for finances. If something happens to your father, the spouse already has authority over the assets. But a durable power of attorney for finances is still a good idea. That's because one spouse may become incapacitated at the same time, or soon after, the other. Or, a separate asset or income might later come to your parent without his spouse's name on it.