If one of your parents has dementia, it’s only a matter of time before they’ll need help with almost every part of their daily life. “They’re going to get to a point where they no longer have the capacity or the ability to sign documents, to understand what they’re signing, and to handle their affairs,” says Stuart H. Schoenfeld, an elder law attorney and partner at Capell Barnett Matalon & Schoenfeld in New York City.

Don’t assume that being the child will give you automatic control over your parent’s financial and health care decisions. It won’t. For that you’ll need a power of attorney.

A survey from the Palliative and Advanced Illness Research Center at PennMedicine finds that only one-third of Americans have a power of attorney in place. Without this document, you could find yourself in a costly, and stressful guardianship process.

What is a power of attorney?

A power of attorney is a legal document your parent signs to allow you, another family member, or a friend to make financial and medical decisions for them when they can no longer make those decisions. Contrary to popular belief, a power of attorney isn’t a person. The person who the power of attorney authorizes to make decisions is called the agent.

This document comes in three types:

• A financial power of attorney lets you make financial decisions—for example, managing your parent’s bank accounts and investments.

• A health care power of attorney gives you the authority to make medical decisions on behalf of your parent. You can talk to their doctor, see their medical records, and decide on treatments. In some states, this document is called a health care proxy.

• A durable power of attorney means that the document remains in effect after your parent becomes incapacitated.

How do you get a power of attorney?

To start the process, contact an elder care attorney. Often the financial and health care power of attorney come packaged as part of an estate plan that also includes a will and a living will, says Annabel Bazante, an elder law attorney practicing in Elmont, NY. The typical cost for a financial and health care power of attorney is under $1,000, while the whole estate plan package runs around $2,000, she adds.

The first thing the lawyer will do is determine whether your parent has the mental capacity to appoint a power of attorney. “One of the main things they’re looking for is, do they understand what they’re doing? Do they understand the power they are bestowing?” says Natali Edmonds, Psy.D., board-certified geropsychologist and founder of the dementia care consulting and support program, Dementia Careblazers in Phoenix, AZ.

In other words, your parent must be cognitively aware enough to know what they’re signing. She suggests having your parent sign the paperwork at a time of day when they’re typically most alert.

Don’t be surprised if the lawyer asks to talk to your parent privately. Your parent is the client, not you, stresses Bazante. The lawyer will want to make sure you’re following your parent’s wishes. “Even if the child is well-intentioned, the parent may not want that child alone to have decision-making power,” she says.

Choosing an agent

It’s not up to you to choose an agent. That decision falls on your parent.

For the financial power of attorney, the best option is someone who has an aptitude for money, suggests Kelly O’Connor, a certified senior advisor, certified dementia practitioner, and elder care consultant in Denver, CO.

While it’s possible to manage finances from far away, she recommends that the health care agent be someone who lives close by, so they can go to medical appointments. Having only one person in the role will make the decision-making process much easier (and some states mandate it). “Because let’s say there are three—A, B, and C—agents under the power of attorney. Agent A wants to continue medical treatment, B does not want to continue medical treatment, and C wants to ask their spouse and is indecisive… What does the medical professional do?” O’Connor says.

Sooner is better

The time to get a power of attorney is before a dementia diagnosis. If that’s not possible, then get one while your parent is still aware enough to sign. “If you wait too long, they might not have the capacity. Then a power of attorney might no longer be an option and we’re doing the more time consuming, costly, and emotionally draining journey of trying to get guardianship,” says Edmonds.

Her own father refused to get a power of attorney until he had a bad fall and she needed to make medical decisions for him. “Unfortunately, what many families find is that it sometimes takes an emergency situation to get these things in place,” she says.

A parent with dementia might balk at a power of attorney as yet another looming threat to their independence. Edmonds suggests that you frame it like an insurance plan. “I hope we never have to use this, but if something does happen, we’ll be so glad that we have it.”