Medicare Part A SNF eligibility rests on four requirements: a qualifying inpatient hospital stay of at least three consecutive days, admission to a Medicare-certified SNF within 30 days of hospital discharge, a physician order certifying the need for skilled care, and an active clinical need for skilled nursing or therapy services at the time of admission. All four must be confirmed before the resident arrives. Not before the claim submits. Before the resident arrives.
That distinction is where most SNF eligibility denials originate. The FY 2024 Medicare Fee-for-Service improper payment rate was 7.66%, totaling $31.7 billion, with insufficient documentation and failure to demonstrate medical necessity cited as the two primary drivers (Source: CMS FY 2024 HHS Agency Financial Report). The residents who generated those denials were not ineligible. Their eligibility was verified at the wrong stage of the admissions process, when nothing could be corrected.
This post is written for billing coordinators and admissions teams who want to know exactly how to verify each requirement, what to document before the first claim drops, and what the denial codes tell you when something breaks down. For the full pre-admission verification workflow across all payer types, see our guide to pre-admission eligibility verification for skilled nursing facilities.
The Four Medicare Part A SNF Eligibility Requirements
Medicare Part A does not cover SNF care automatically for every enrolled beneficiary. Coverage requires four specific conditions, met simultaneously. Each one is independently verifiable. Each one produces a predictable denial code when missed.
Requirement 1: The 3-Day Qualifying Inpatient Hospital Stay
To qualify for Medicare Part A SNF coverage, a resident must have been formally admitted as an inpatient to a Medicare-approved acute care hospital for a minimum of three consecutive days. The admission day counts. The discharge day does not. The 30-day window to enter the SNF begins at discharge.
This is the requirement most billing coordinators verify least carefully, and the one most likely to be wrong by the time they check.
The reason is observation status. A resident can spend four or five days physically in a hospital, in a hospital bed, receiving nursing care, and still have zero qualifying inpatient days for Medicare SNF purposes. When the hospital classifies a stay as outpatient observation rather than inpatient admission, those days do not count. That classification is made entirely on the hospital side. It does not appear on most referral paperwork. The SNF billing team will not see it unless they ask.
The verification step: Before clinical acceptance is confirmed, ask the hospital discharge planner directly: “Was the patient formally admitted as an inpatient, or held under observation status, for each day counted toward the qualifying stay?” If any days were classified as observation, Condition Code 30 on the hospital claim, those days are out. A patient who appears to have a four-day hospital stay may have a one-day qualifying stay. That is a failed admission under Medicare Part A, and the bed has already been offered.
Requirement 2: Admission to a Medicare-Certified SNF Within 30 Days of Hospital Discharge
The 30-day window begins at hospital discharge, not at the date the referral arrived, not at the date the family signed paperwork. Day 31 is a disqualification regardless of how cleanly every other requirement was met.
Two verification points here that billing teams sometimes skip. First, confirm the facility’s Medicare certification status is currently active. Certification status can lapse. A facility certified last year is not automatically certified today. Check CMS Care Compare or CASPER before the admission date, not after. Second, document the hospital discharge date and the SNF admission date explicitly in the record with the day count stated. If the transfer happened on Day 29 or Day 30, that needs to be visible. An auditor should not have to calculate the window from scattered admission documents.
Requirement 3: A Physician Order Certifying the Need for Skilled Care
A physician must certify that the resident requires daily skilled nursing care or skilled therapy services at least five days per week. That certification must be in the medical record at or before the time of admission, not chased down after the resident arrives, not added to the record after the claim is ready to drop.
Facilities that admit on a Friday with a plan to get the certification signed Monday have created a billing gap. The date on the certification matters. If it postdates the admission, the claim is vulnerable in any audit, and the absence of a timely order is one of the most cited documentation deficiencies in SNF post-payment reviews.
Verification ownership is straightforward: the DON or charge nurse confirms the signed order exists before the bed is assigned. The business office confirms it is in the record before the first billing date. Neither step substitutes for the other. Both need to happen.
Requirement 4: Active Need for Skilled Nursing or Therapy Services
Skilled care under Medicare Part A means services that can only be safely and effectively performed by or under the supervision of a licensed nurse or therapist. Custodial care, help with bathing, meals, mobility, does not qualify on its own. The need must be active at admission, not historical.
For billing teams, this requirement is the foundation of the KX modifier and the Triple Check process. If the clinical documentation does not support an active skilled care need at the time of billing, the claim does not hold up in a RAC or TPE audit. The physician certifies the need. The nursing assessment and therapy evaluations must corroborate it. A mismatch between the two is an audit finding, not a documentation gap that can be fixed after the fact.
The Benefit Period: What Billing Teams Actually Need to Verify
A Medicare Part A benefit period begins the day a resident is admitted to a hospital or SNF as an inpatient. It ends the day the resident has been out of all inpatient care settings, hospital and SNF combined, for 60 consecutive days. Each benefit period provides up to 100 days of SNF coverage. A new benefit period, with a full 100-day maximum, begins after the 60-day gap resets.
Under the CY 2026 cost structure established by CMS, Medicare covers SNF care in full for Days 1 through 20 of each benefit period, with a daily coinsurance of $217 for Days 21 through 100, and full resident responsibility after Day 100 (Source: Federal Register, November 19, 2025).
Here is the assumption that generates more avoidable denials than almost anything else in SNF billing: that active Medicare Part A enrollment means SNF days are available.
It does not. A resident can carry active, confirmed Medicare Part A coverage and have zero SNF days remaining in the current benefit period, because a prior stay used them, and the 60-day reset clock has not yet completed. The enrollment is active. The SNF days are gone. A billing coordinator who verifies enrollment and stops there has confirmed the resident has Medicare. They have not confirmed the resident has SNF coverage for this admission.
Verifying both requires two separate lookups in HETS: enrollment status, and benefit days remaining in the current period. One is not a proxy for the other. If the days-remaining field shows zero, the admission is not covered under Medicare Part A, regardless of what the enrollment field shows. The family conversation that follows a post-admission discovery of this is far harder than the pre-admission question would have been.
For the step-by-step Medicare eligibility verification process, see our Medicare eligibility verification guide.
What the Observation Hours Exclusion Actually Means at the Admissions Desk
The observation status problem is simple in concept and easy to miss in practice. Hospitals use observation classification to manage their own readmission metrics and billing exposure. It is a legitimate decision made entirely on the hospital side. Its impact on SNF billing eligibility is total: observation days count for nothing under the three-day qualifying stay requirement, and it is invisible on most referral packets.
The discharge summary does not flag it. The referral form does not flag it. Nothing in the standard referral workflow surfaces it unless the admissions coordinator asks the discharge planner a direct question before clinical acceptance is confirmed.
A facility that accepts a referral, offers a bed, and calls the family before running this check has no good options when the observation status issue comes back. The admission has already happened. The conversation with the family about coverage is already one step harder. And if no alternative payer was confirmed in advance, the billing path forward is unclear.
This is not a situation where faster billing software helps. It is a situation where the admissions coordinator needs to ask one question earlier in the workflow than most SNF teams currently do.
Why Your Medicare Part A Verification Is Probably Running at the Wrong Stage
Most SNF billing teams treat Medicare Part A eligibility verification as a billing function. It is assigned to billing because billing submits the claim. The logic is obvious. The problem is that the claim is the final event in the admissions sequence, and the verification needs to happen at the first.
By the time billing runs the check, the referral has been accepted, the bed has been offered, the family has been told there is a room, and the physician certification is being tracked down. Discovering a qualification failure at that point does not undo the admission. It documents a denial that was built in the moment clinical acceptance was confirmed without a payer verification in hand.
If your eligibility check runs after the admission decision, you are not verifying coverage. You are documenting a denial that has already happened.
The fix is a role assignment change, not a better tool. The admissions coordinator owns pre-admission verification at referral intake: confirming the qualifying stay, checking benefit days remaining, and identifying observation status issues before clinical acceptance is extended. The business office manager owns mid-stay coverage monitoring: tracking benefit period milestones and flagging coverage lapses before billing is affected. Billing submits a claim against a record that has already been verified at two separate stages, not a record that billing is verifying for the first time.
LTC Apps Eligibility Verification runs within the same platform as Admissions. No separate portal, no separate login. Every verification result is stored against the resident’s record, accessible to both admissions and billing without any workflow gap between the two teams. Learn more about the LTC Apps Eligibility Verification module.
For the complete three-stage verification model, pre-admission, mid-stay, and post-denial root cause, see our SNF eligibility verification workflow guide.
Denial Codes That Fire When Medicare Part A Eligibility Breaks Down
Each eligibility failure produces a specific denial code. The code identifies which requirement failed, and whether the claim has any rework path.
CO-27: Expenses incurred after coverage terminated. On a Medicare Part A SNF claim, this almost always means one of two things: the benefit period was already exhausted at the time of admission, or Part A enrollment had lapsed. Neither is reworkable without an alternative payer. The root cause is a verification that pulled enrollment status without pulling benefit days remaining.
CO-22: This care may be covered by another payer. In the SNF context, this often means the resident was enrolled in a Medicare Advantage plan and the claim was filed to Original Medicare instead, or a prior payer should have been billed first. CO-22 is sometimes reworkable if the correct payer can still be billed within timely filing limits.
PR-204: Service not covered under the patient’s current benefit plan. This fires when the skilled care requirement was not supported by clinical documentation, or when the physician certification did not align with the level of care being billed. PR-204 is the denial code most closely associated with audit findings on the skilled care requirement. Without strong clinical documentation already in the file, it is the hardest category to recover from.
CO-96: Non-covered charge. This signals a specific service delivered during the stay after the skilled care need was no longer clinically supported, a mid-stay coverage break that the business office did not catch before billing continued through it.
The denial code is the end of a chain, not the beginning of a new problem. CO-27 does not mean the claim was filed incorrectly. It means the admissions verification did not include a benefit days remaining check. Every eligibility denial should trigger a 10-minute root cause audit: which requirement failed, at which stage, and who owned that stage? Facilities that treat each denial as a standalone billing correction event replay the same sequencing error on the next admission.
Audit activity in the nursing home sector is expanding, with CMS’s Unified Program Integrity Contractors now authorized to withhold or suspend Medicare payments and refer cases to law enforcement for civil or criminal prosecution when improper billing patterns are identified (Source: Skilled Nursing News, December 2025). The documentation standard for Medicare Part A eligibility is not a compliance formality. It is the only defense a facility has when an auditor asks why a claim was submitted without a confirmed qualifying stay.
What Billing Teams Must Document Before the First Claim Drops
The four eligibility requirements each carry a documentation standard. In a RAC, TPE, or OIG audit, these are the records the auditor pulls first. Having them in the file before the first claim drops is not audit preparation. It is the standard the claim is built on.
Three-day qualifying stay: A copy of the hospital face sheet showing inpatient admission status, admission date, and discharge date. If any days were under observation status, written confirmation from the hospital discharge planner identifying which specific days carried inpatient status. The discharge summary alone is not sufficient. It typically does not specify admission status at the day level.
30-day transfer window: Hospital discharge date and SNF admission date, both documented explicitly, with the day count stated. If the transfer happened on Day 28, 29, or 30, make it visible. Do not leave an auditor to reconstruct the timeline from scattered admission documents.
Physician certification: Signed physician order certifying daily skilled care need, with physician name, NPI, and signature date on or before the admission date. Retroactive certifications are a consistent audit finding and a consistent claim vulnerability.
Skilled care need: Nursing assessment findings and therapy evaluations that corroborate the physician’s certification. The clinical record must support the level of care being billed. A physician’s certification and a nursing assessment that describe two different clinical pictures is not a documentation gap. It is an audit finding in the making.
For the complete documentation and verification framework across all payer types, see our complete SNF eligibility verification guide.
FAQ: Medicare Part A SNF Eligibility
Medicare Part A covers up to 100 days of SNF care per benefit period. Days 1 through 20 are covered in full. Days 21 through 100 carry a daily coinsurance of $217 in 2026. After Day 100, the resident pays all costs unless a Medigap or supplemental policy covers the remainder. A new 100-day maximum becomes available once the resident has been out of all inpatient settings, hospital and SNF combined, for 60 consecutive days, resetting the benefit period.
No. Observation status days do not count toward the three-day inpatient qualifying stay, regardless of how many days the patient spent physically in the hospital. Only days with a formal inpatient admission order count. SNF billing teams must confirm the admission classification of each counted day with the hospital discharge planner before extending clinical acceptance under Medicare Part A.
In medical billing, a skilled nursing facility is a Medicare-certified provider delivering post-acute care that requires daily skilled nursing or licensed therapy services. For Medicare Part A billing purposes, a SNF stay is only covered when all four eligibility requirements are met and documented before the claim submits. Not all nursing homes are Medicare-certified. Active certification status must be verified at the time of each admission, not assumed from a prior certification check.
A Medicare Part A beneficiary is eligible for covered SNF care when four requirements are simultaneously met: a minimum three-day qualifying inpatient hospital stay, admission to a Medicare-certified SNF within 30 days of hospital discharge, a signed physician order certifying the need for skilled nursing or therapy services, and an active clinical need for those services at the time of admission. All four are required. Three of four is a denial.
The claim is denied. CO-27 fires when the benefit period was exhausted or Part A was inactive. PR-204 fires when the skilled care requirement was not clinically supported. If no alternative payer was confirmed at admission, the billing path forward may not exist. Most eligibility-driven denials are not reworkable. They result in write-offs. The only point in the admissions process where the outcome can change is before the bed is offered.
Who This Is For
LTC Apps Eligibility Verification is the right fit if your billing team is running Medicare and Medicaid eligibility checks across separate payer portals, logging in to one system for Part A enrollment, another for benefit days remaining, with no single verification record attached to the resident’s admissions file. The module runs both checks within the same platform as Admissions, stores every result against the resident’s record, and gives both the admissions coordinator and the business office access without any additional login or tool. See the LTC Apps Eligibility Verification module for details.
This is not the right fit if you need a full clinical EHR with physician-facing charting, or a developer-configurable eligibility API for custom system integration. LTC Apps is a modular operations platform built for SNF workflows.
What Happens After You Request a Demo
The process takes less time than most facilities expect. A member of the LTC Apps team reaches out within one business day to schedule a call. The demo is a 30-minute live walkthrough of the modules most relevant to your situation, Eligibility Verification, Admissions, or both. Pricing specific to your facility size and module selection is covered during that same call.
Most facilities have a clear answer on fit and pricing within one week of first contact.
One note if you are mid-contract with your current vendor: a parallel evaluation now means you make a decision on your timeline at contract end, not under the pressure of a deadline you did not choose.
If your Medicare Part A eligibility verification is running after the admission decision rather than before it, and your denial volume reflects that, LTC Apps was built to fix exactly that workflow.
