The Medicare 100-day nursing home benefit, explained

There is exactly one nursing-home situation Medicare pays for, and confusion about it causes some of the most expensive surprises in senior care. It covers short, skilled rehabilitation after a hospital stay — not long-term care.

First: whose rulebook are you reading?

Everything below describes Original Medicare. About half of the people on Medicare are instead in a Medicare Advantage plan, and for them this page is the wrong book. An Advantage plan is allowed to waive the three-day hospital requirement entirely — some do — and it sets its own cost-sharing for a skilled-nursing stay, which can mean copays starting on day 1 rather than day 21, and daily amounts that have nothing to do with the figures here. It may also require prior authorization and steer you to facilities in its network.

So before you plan around any number on this page, look at the insurance card. If it says anything other than Medicare — a plan name, an insurer’s logo — call the number on the back and ask what that plan requires and charges for skilled nursing. The rules below are still worth reading, because they are the floor the plan is measured against and the vocabulary everyone in the building will use. They are just not your bill.

The 3-day rule

To qualify, you generally need a qualifying inpatient hospital stay of at least three days (nights count; observation status does not). Then, within 30 days, you enter a Medicare-certified skilled nursing facility for care related to the hospital condition, ordered by a doctor.

Observation status — the trap inside the 3-day rule

This is the most expensive misunderstanding on this page, and it is worth the next five minutes even if you skip everything else.

A person can spend four nights in a hospital bed, in a gown, wearing the wristband, eating the hospital food, and still be an outpatient the entire time — because the hospital classified the stay as observation rather than admitting them. Observation nights do not count toward the three days. Nothing in the hallway looks different. Only the paperwork differs, and the paperwork is the only thing Medicare reads. Families usually find out weeks later, when the nursing home hands them a bill for the whole stay and the 100-day benefit turns out never to have existed.

Ask — and then make them put it in writing

Ask out loud, every single day: “Is my mother an inpatient, or is she under observation?” Ask the case manager, not the nurse at the bedside, who often doesn’t know.

You are also entitled to be told without asking. When someone on Medicare receives observation services as an outpatient for more than 24 hours, the hospital must give them a written notice and an oral explanation of it — no later than 36 hours after the observation services started, or sooner if the person is admitted, transferred, or sent home first. The form has a name: the MOON, the Medicare Outpatient Observation Notice. It has to say why the person is on observation and what that means for their cost-sharing and for skilled-nursing coverage afterward, and someone has to sign it. If your parent has been in that bed past a day and nobody has handed you one, ask the case manager for the MOON by name — using the word tends to change the conversation. This one applies whether the coverage is Original Medicare or an Advantage plan.

The notice requirement is 42 CFR § 489.20(y) (Cornell LII ↗); the form itself is CMS-10611.

If they were admitted first and then switched, you can appeal

For years, a hospital could admit someone as an inpatient, reclassify the stay as observation days later, and there was simply nothing to appeal — the decision was treated as the hospital’s to make. That changed. After a class action called Alexander v. Azar, Medicare now runs an appeal aimed squarely at that reclassification, and it has been open since February 14, 2025.

Read this next part carefully, because the door is narrower than the headlines suggest. The appeal is for a person who was formally admitted as an inpatient on a doctor’s order and then reclassified by the hospital as an outpatient on observation. It does not help the more common situation where someone was placed on observation from the start and never admitted at all — that remains a gap, and no amount of arguing on the ward changes it. On top of that, one of two things must also be true: the person was in the hospital three or more consecutive days but an inpatient for fewer than three, or they weren’t enrolled in Part B during the stay.

If that describes your parent, the hospital should hand you a Medicare Change of Status Notice, and it carries the phone number of the Quality Improvement Organization — the outside reviewer that decides these. Call it before your parent leaves the hospital and you get the expedited version, decided in about a day, while the answer can still change where they go next. Miss that window and a standard appeal is still available afterward, just without the speed. It costs nothing. Your free SHIP counselor will do it with you, and this is exactly the kind of call they are for.

Eligibility and the expedited process are at 42 CFR §§ 405.1210 (who qualifies ↗) and 405.1211 (expedited review ↗), from the final rule at 89 FR 83240 (October 15, 2024), effective October 11, 2024. There was also a one-time window to appeal old stays going back to 2009; it closed on January 2, 2026, so if you read elsewhere that decades of stays can be reopened, that is out of date.

What it costs and covers

Medicare covers up to 100 days per benefit period, but not evenly: days 1–20 are fully covered; days 21–100 carry a daily coinsurance ($217 a day in 2026) unless a supplement pays it; after day 100 you pay everything. That coinsurance is set each year at one-eighth of the Part A hospital deductible ($1,736 in 2026), so it rises annually — a full run from day 21 to day 100 is roughly $17,000 out of pocket if nothing else covers it. It covers skilled nursing, physical/occupational/speech therapy, and related services — the goal is recovery, not permanent living.

Why it usually ends before 100 days

The benefit continues while skilled care is needed. Most stays end well before day 100 — but often for the wrong reason, and this is the single most valuable thing on this page.

Facilities routinely tell families that Medicare stops once a patient “plateaus” or is “no longer making progress.” That is not the rule. Under the Jimmo v. Sebelius settlement, CMS is explicit that coverage does not turn on the presence or absence of potential for improvement: skilled nursing and skilled therapy are covered when they’re needed to maintain the person’s condition or to prevent or slow deterioration, as long as the care requires a skilled professional to be done safely and effectively. Plateaus are normal in stroke and similar recoveries. A plateau alone is not a lawful reason to cut coverage off.

What does legitimately end the benefit: the care is no longer skilled (an aide or family member could safely do it), the person no longer needs daily skilled care, or the 100 days run out. If you’re told coverage is ending because a parent stopped improving, ask for the notice in writing and appeal — the notice must explain how, the fast-appeal process costs nothing, and this is exactly the denial the Jimmo standard exists to correct. Your free Long-Term Care Ombudsman and your State Health Insurance Assistance Program (SHIP) counselor will help you do it.

The trap

Families hear “Medicare covers the nursing home” and assume it covers a permanent stay. It does not. When rehab ends and ongoing care is needed, you’re into long-term-care payment — private pay, then Medicaid. Plan for that gap before it arrives; the drawdown calculator shows how fast it changes the math.

This guide is general information, not medical, legal, or financial advice. Rules vary by state and change over time. For personalized, unbiased help, your Area Agency on Aging and your state’s Long-Term Care Ombudsman are free.