A Fall at 75, Three Weeks of Rehab — and Medicare’s Day-21 Copay Starts the Bills

A 75-year-old trips on a rug, fractures a hip, and spends four nights in the hospital before her doctor recommends three weeks of inpatient rehab at a skilled nursing facility. She has Original Medicare and assumes Part A will carry her through recovery. It may, but only if the hospital stay qualifies. And if rehab runs past 20 days, a daily coinsurance bill kicks in that many beneficiaries never see coming.

The risk is highest for people on Original Medicare without a Medigap plan, or families helping a parent in that situation. Medigap Plan G and Plan N both cover skilled nursing facility coinsurance, but the hospital-status rule still matters because the SNF stay must qualify for Medicare coverage in the first place.

The Trap Before the Copay: Observation Status

Before the day-21 bill matters, one rule decides whether Medicare pays anything at all for the SNF. The stay generally qualifies only if the patient had a medically necessary inpatient hospital stay of at least three consecutive days, not counting the discharge day. A stay billed as observation, even in the same hospital bed with similar care, does not count.

Families often learn this after the fact, when the SNF bill arrives with no Medicare coverage at all. Ask the hospital, in writing, whether the patient is inpatient or under observation on day one. If the doctor expects rehab afterward, ask the physician and case manager whether inpatient admission is medically supported before the qualifying-stay clock runs out.

The Day 21 Math

Assume the three-day inpatient rule is satisfied. Under 2026 rules, the SNF coinsurance schedule works like this:

• Days 1 through 20: Medicare pays 100%. The patient owes $0.
• Days 21 through 100: The patient owes $217.00 per day in coinsurance, up from $209.50 in 2025.
• Day 101 and beyond: Medicare pays nothing. The patient owes the full cost.

Three weeks of rehab ends on day 21. The first billed day costs $217. That single day sounds manageable. The problem is that hip fractures rarely resolve in three weeks. If the rehab team extends the stay to 30 days, the patient owes $2,170 in coinsurance. Extend it to 50 days and the tab reaches $6,510. Ride the benefit out to day 100 and the coinsurance alone totals $17,360, on top of the $1,736 Part A hospital deductible from the admission that started the whole benefit period.

Why This Bill Lands Harder in 2026

The SNF coinsurance rose $7.50 per day in 2026, from $209.50 to $217.00, a 3.6% increase. Social Security beneficiaries received a 2.8% COLA for 2026. The gap is small on one day of rehab, but it grows quickly over a longer stay. A 50-day SNF stay now costs $225 more in coinsurance than it would have under the 2025 daily rate.

Two Products That Actually Close the Gap

Original Medicare has no out-of-pocket maximum, and the SNF coinsurance is the exposure most enrollees underestimate. Two supplements neutralize it:

• Medigap Plan G pays the full SNF coinsurance for days 21 through 100. Once you clear the annual Part B deductible of $283 in 2026, Plan G covers this bill entirely. Premiums typically run $150 to $300 per month depending on state and age.
• Medigap Plan N also covers the SNF coinsurance in full, at a lower premium, in exchange for small office and ER copays elsewhere.

Medicare Advantage plans handle this differently. Most cap in-network out-of-pocket spending at several thousand dollars, but SNF cost-sharing and network restrictions vary by plan, and the facility your hospital recommends may sit outside the network.

What to Do

1. Confirm inpatient status in writing on hospital day one. If the record says “observation,” ask the attending physician to reassess before the third midnight. Without three inpatient midnights, Medicare pays nothing toward the SNF.
2. If you are within six months of your Part B start date, apply for Medigap Plan G or Plan N now. After that window closes, insurers in most states can medically underwrite and deny you. A hip fracture on record makes later approval unlikely.
3. If the window has closed and you are on Medicare Advantage, read the SNF benefit in your Evidence of Coverage before you need it. Know the daily copay schedule, the in-network SNF list, and the out-of-pocket maximum. That document is what the plan will pay against, not the enrollment brochure.

The Rehab Bill Starts Before Rehab Does

The day-21 SNF coinsurance is not the first Medicare decision after a fall. The first decision is whether the hospital stay is inpatient or observation, because that status can decide whether the SNF benefit opens at all. Once it does, the next question is whether the beneficiary has Medigap or another plan that absorbs the daily coinsurance. Without that backup, a longer recovery can become a five-figure bill.

Figures reflect 2026 plan year rules from the CMS fact sheet on 2026 Medicare Parts A & B Premiums and Deductibles, released November 14, 2025.

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