The three conditions are the whole test, and they are conjunctive. 42 CFR 409.42 says a beneficiary must meet each of them. Under (a) the beneficiary must be confined to the home, or in an institution that is not a hospital or a skilled nursing or nursing facility. Under (b) the beneficiary must be under the care of a physician or allowed practitioner "who establishes the plan of care". Under (c) the beneficiary must need at least one of: intermittent skilled nursing services, physical therapy, speech-language pathology services, or, in the circumstances the paragraph sets out, occupational therapy. Paragraphs (d) and (e) add that the care must be under a plan of care meeting §409.43 and must be furnished by, or under arrangements made by, a participating home health agency.
Medicare.gov puts the homebound condition in a form a family can apply. Both of two things must be true: leaving home "isn't recommended because of your condition" or you have trouble leaving without help such as a cane, wheelchair, walker, crutches, special transportation or another person; and you are "normally unable to leave your home and leaving takes a lot of effort". Medicare adds two clarifications that matter in practice: short, infrequent absences for non-medical reasons such as religious services are allowed, and, in Medicare's own words, "You can still get home health care if you attend adult day care."
Now the part that costs families the most money to misunderstand. Medicare.gov's list of covered services includes "Part-time or intermittent home health aide care", and then states the condition in a parenthesis: "(only if you're also getting skilled nursing care, physical therapy, speech-language pathology services, or occupational therapy at the same time)". So personal care is not excluded because it is personal care. It is covered as a dependent service that rides on a qualifying skilled need, and it stops the moment that need does.
The exclusion that then bites is 42 CFR 411.15(g), which reads in full: "Custodial care, except as necessary for the palliation or management of terminal illness, as provided in part 418 of this chapter. (Custodial care is any care that does not meet the requirements for coverage as SNF care as set forth in §§ 409.31 through 409.35 of this chapter.)" Two things are worth noticing. The definition is negative: custodial care is defined as whatever fails the skilled test, rather than by describing the tasks. And the exception written into the exclusion is the hospice benefit. It is not the only route around the exclusion, since 42 CFR 460.94(b)(5) also waives §411.15(g) for services furnished to a participant in a PACE program, but for a household outside hospice and outside PACE the exclusion is the operative rule.
The four things Medicare names as not covered are worth memorizing because each one is a real household expense: 24-hour-a-day care at home; home meal delivery; homemaker services such as shopping and cleaning that are unrelated to your care plan; and, in Medicare's words, "custodial or personal care that helps you with daily living activities (like bathing, dressing, or using the bathroom), when this is the only care you need."
How much care the benefit actually delivers. Medicare.gov states that if you qualify you can get unlimited home health visits, and that "in most cases, 'part-time or intermittent' means you may be able to get skilled nursing care and home health aide services up to 8 hours a day (combined), for a maximum of 28 hours a week", with the possibility of more for a short time, under 8 hours a day and up to 35 hours a week, where the provider decides it is necessary. That is a real amount of help. It is also capped, intermittent, and tied to a skilled need, which is why it does not solve a continuous-supervision problem.
What is left, and who pays for it. Ongoing custodial care at home has four ordinary funding routes, and a household usually ends up using more than one. Private payment out of income and savings is the default. A long-term care insurance policy pays when its own benefit triggers are met, which are written around activities of daily living and cognitive impairment rather than around Medicare's skilled test, so a policy can be paying at exactly the point Medicare stops. A Medicaid home and community-based services waiver can fund care at home for someone who meets both the state's level-of-care test and its financial tests. And for a qualifying wartime veteran, 38 U.S.C. 1521(d) provides an increased pension rate where the veteran "is in need of regular aid and attendance", reduced by the veteran's annual income; 38 U.S.C. 1541(d) does the same for a surviving spouse who is entitled to pension and is in need of regular aid and attendance. Both rates are adjusted annually.
A structural note on cost sharing that surprises people. For covered home health services the beneficiary pays nothing, which is unusual in Medicare. But equipment is separate: after the Part B deductible, the beneficiary pays 20 percent of the Medicare-approved amount for Medicare-covered durable medical equipment. So a benefit that is free can still generate a bill, and the bill is for the walker rather than for the nurse.