But where would he go — and how would we pay for it? Could he stay in his apartment if he had regular visits from an aide? Or should he go to an assisted-living facility where there would be more services available for him?

So began my family’s crash course in caring for an aging parent in declining health.

If you’re in this predicament, you know already there is no simple answer. Older people each have unique medical and emotional needs. And finances often dictate how far you can go in creating the ideal situation for them.

That is what Linda Chase, a lawyer in Reston, Va., realized after running the numbers on what it would cost for home care for her mother, who has dementia and needs round-the-clock attention.

“We couldn’t afford private home-health care, so the only option for us was assisted living in a facility with dementia care,” Ms. Chase said.

Below, I offer guidelines and considerations that can help you make an informed — if not always easy — decision about what type of housing will support your parent’s needs, without bankrupting the family in the process.

And note: While the following discussion refers to a single parent who lives alone, many of the considerations would also apply to an elderly couple who are each in declining health.

IS HOME STILL SAFE?

If your parent is living at home, he or she probably wants to stay there. If that’s the case, hire an expert, like a geriatric care manager, who can assess whether your parent will be able to manage at home and what kind of support will be needed.

A geriatric care manager, who charges $50 to $200 an hour, will look at how your parent functions in the space — able to cook? able to manage medications?— and may suggest modifications. These may include adding grab bars and removing throw rugs, to make the home safer. If your parent will be in a wheelchair, the care manager can figure out whether doorways need to be widened or a stair lift should be added.

In a column last fall, I offered fuller advice on how to find a geriatric care manager, but here are a few basics:

Ask friends for references or contact the National Association of Professional Geriatric Care Managers . If money is tight, call the local federally funded office on aging to find the nearest one.

“The office should be able to send a case manager to your parent’s home to do a home assessment at no charge,” says Chris Stone, a registered nurse and clinical liaison for LifeQuest Nursing Center, in Quakertown, Pa.

Next, determine what kind of day-to-day care your parent requires. A care manager or your parent’s doctor should be able to help you figure this out. Some older people can manage surprisingly well with minimal help. But parents with dementia or a chronic medical condition may require a full-time aide, and the cost of that can add up quickly.

According to a survey by Genworth Financial, an insurance company that sells long-term care policies, the median hourly rate for a licensed caregiver ranges from $18 to $46 an hour, depending on the qualifications of the aide. The cost runs on the higher side if the aide works for a Medicare-certified agency.

To learn about rates in your area, call a local home health care agency, said Vanessa Bishop, president of Elder Care Consultants, in Reston, Va. If you do opt for in-home care, be sure to use an agency that is licensed, bonded and insured, Ms. Bishop says, and one that conducts thorough background checks on its employees.

THE ASSISTED-LIVING OPTION

Even if parents insist on remaining in the home, doing so may not be in their best interests. A parent in failing health or somehow impaired is not the only one in jeopardy; other family members may be under a lot of stress, too. It can also be lonely and isolating for a parent to stay at home.

Assisted-living residences, which have proliferated in recent years, have small apartments that residents can furnish with their own belongings, along with a common dining room where meals are served, a nurse’s office where prescription drugs are dispensed and activity rooms for socializing. The great advantage of such places is that you can ramp up the level of care as your parent needs it, adding services like help with dressing and bathing. Many have special wings or floors for people with Alzheimer’s. My sisters and I ultimately decided to move our dad to an assisted-living facility in Ardsley, N.Y., just across the river from his previous home. He wasn’t keen on the idea at first, but the move turned out well for him and for us. He has his own studio apartment, but he doesn’t have to cook, clean, do his laundry or think about which pill to take when.

And he has a built-in social network of other residents and the bustling staff. (In fact, he often prefers the young staff to the residents.) We all have less to worry about.

WHAT CAN YOU AFFORD?

Ultimately, it may all come down to money. Find out how much your parent has and whether he or she bought long-term care insurance. If the assets are plentiful, you may need to see a financial planner for advice on how to stretch the funds over time.

We were able to pay for my dad’s rather steep assisted-living bill through a combination of his annual income and the proceeds from the sale of his apartment.

It might also be wise to speak with an elder-law lawyer, who can explain when your parent might qualify for government programs like Medicaid. Medicaid does not cover the costs of assisted living, but it does cover care provided in nursing homes.

“Everyone thinks Medicaid is only for the poor, and that you have to impoverish yourself to be eligible,” says Robert S. Bullock, a lawyer in Washington and a senior partner of the Elder and Disability Law Center, “But it’s not.”

COMPARE COSTS

Add up the costs that would be involved in keeping your parent at home, including home upgrades, caregivers, rent, mortgage payments and taxes. Factor in what long-term care insurance will cover, if there is any.

If your parent is a military veteran, find out if he or she is eligible for the Aid and Attendance Pension benefit, which provides a monthly stipend of up to $1,632 (or $1,949 for couples), to veterans who need help with basic daily tasks, like eating and dressing.

Once you have an idea of what it would cost to keep your parent at home, the decision might be made for you. The Genworth survey found that the median cost for an assisted-living facility was $34,000 a year, which translates into about 30 hours a week of home care at $20 an hour. But in major urban areas the cost for assisted living can be twice or even three times that amount.

Even so, assisted living sometimes works out to be a better deal, as Ms. Chase, the lawyer in Virginia, learned. When she did her research, Ms. Chase found it would cost around $150,000 a year to hire full-time home caregivers for her mother, Jeanette Chase.

“It was a horrendous amount of money,” Ms. Chase said.

A nearby assisted-living facility, on the other hand, charged $80,000 a year for a room on a secure floor intended for memory-impaired patients. And her mother’s long-term care insurance, which did not cover in-home care, covered 40 percent of the bill for assisted living.

Even assisted living “was expensive — but worth it,” Ms. Chase said. “I was able to continue working and she was safe and nearby.”