SNF Billing Guidelines for Medicare Part B: What Skilled Nursing Facilities Need to Know

Medicare Part A gets most of the attention in SNF billing it governs post-acute reimbursement under PDPM, drives MDS coding decisions, and involves the consolidated billing rules that create the most compliance complexity.

But Medicare Part B, binding on skilled nursing facilities is equally important and far more frequently misunderstood. Billing Part B incorrectly or failing to bill it when it applies costs facilities real revenue and creates compliance exposure that surfaces during audit review.

At MCA Medical Billing Solutions, L.L.C., we manage both Medicare Part A and Part B billing for our skilled nursing clients. Here is a practical breakdown of the SNF billing guidelines that govern Medicare Part B.

When Does Medicare Part B Apply in a Skilled Nursing Facility?

Medicare Part B covers outpatient services provided to SNF residents who are not in a covered Medicare Part A stay. Understanding when Part B applies is the first billing decision and getting it wrong generates either a denial or a compliance violation, depending on the direction of the error.

Part B applies in four situations:

• The resident did not have a qualifying three-day inpatient hospital stay observation status does not count toward this requirement, making the resident ineligible for Part A coverage of the skilled nursing stay
• The residents’ Part A benefit days are exhausted: after the 100-day benefit period, Part B may cover continued skilled services if medical necessity is met
• The resident is a long-stay Medicaid resident: receiving certain skilled services not covered by Medicaid in their state
• The resident has waived Part A coverage: in rare situations where a beneficiary chooses not to use Part A benefits for the admission

The critical distinction: Part A covers inpatient skilled care under a singleconsolidatedclaim. Part B covers specific outpatient services billed separately, and each service must individually meet Medicare’s medical necessity and documentation standards.

What this means for your facility: Payer status must be confirmed at admission and monitored throughout the stay. A mid-stay transition from Part A to Part B is a billing event it requires an immediate change in claim type and close attention to the transition date. Errors in handling that transition are one of the most common and costlySNF billingmistakes.

What Medicare Part B Covers in a Skilled Nursing Facility

Skilled Therapy Services

Physical therapy, occupational therapy, and speech-language pathology services provided to residents not in a covered Part A stay can be billed to Medicare Part B when the services are medically necessary and delivered by a qualified therapist.

Each therapy visit must be documented with a treatment note that establishes the skilled nature of the service, the clinical rationale, and the patient’s objective functional response. Generic notes that don’t describe individualized care will not support Part B medical necessity in a TPE review or RAC audit.

Physician and Practitioner Services

Physician visits, nurse practitioner services, and clinical social worker services provided to residents not in a Part A stay are typically billed directly to Part B by the rendering practitioner not by the SNF. Understanding this boundary is essential. When outside practitioners bill Medicare directly for services that should be consolidated under a Part A claim, it creates a billing conflict and a compliance violation.

Diagnostic Services

Certain diagnostic services lab tests, radiology procedures are bundled under consolidated billing when the resident is in a Part A stay. When the same services are provided to a resident not in a Part A stay, they may be billed separately to Part B by the rendering provider. This distinction is one of the most frequently misapplied rules inSNF billing.

What this means for your facility: Your billing team needs current, specific knowledge of what falls under consolidated billing and what doesn’t apply at the resident level on every claim, not just as a general policy. Regular training on consolidated billing exceptions is essential to avoiding the compliance violations that attract RAC and ZPIC attention.

Key SNF Billing Guidelines for Medicare Part B Claims

Type of Bill Code

Part B SNF claims use Type of Bill code 22X. Using 21X the Part A inpatient code on a Part B claim routes it to the wrong payment system and generates an automatic denial. This is one of the most preventable billing errors in SNF settings and one that appears with surprising regularity in facilities whose billing staff manage both Part A and Part B without clear workflow separation.

Revenue Codes

Revenue codes on Part B therapy claims must correctly identify the therapy discipline: 0420–0429 for physical therapy, 0430–0439 for occupational therapy, and 0440–0449 for speech-language pathology. Each code must be paired with the corresponding HCPCS procedure code and supported by documentation in the clinical record. A revenue code without a matching clinical note is a billing error and a common audit trigger.

Medical Necessity Documentation

Every Part B service requires documentation establishing why the service was required at a skilled level. For therapy, that means a completed evaluation, an individualized treatment plan, progress notes with objective functional measurements, and physician orders. Templated notes that don’t describe specific interventions and individual clinical responses will not survive a TPE review or RAC audit.

The Therapy Cap and KX Modifier

Medicare imposes annual financial thresholds on Part B outpatient therapy services. Once a beneficiary’s Part B therapy charges reach the threshold, claims must include the KX modifier to certify that continued services are medically necessary. Omitting the KX modifier when it’s required results in automatic denial. Facilities must track cumulative Part B therapy spend per beneficiary to apply modifiers correctly.

What this means for your facility: Part B billing requires the same level of process discipline as Part A with its own distinct coding, documentation, and compliance requirements. Facilities that treat Part B as a lower priority consistently see higher Part B denial rates and greater audit exposure in therapy billing.

Common Part B Billing Mistakes in SNF Settings

The following errors account for most Part B denials and compliance findings in skilled nursing facilities. If your facility is experiencing higher-than-expected Part B denial rates, review your denial data against these categories first.

• Billing Part B for services that fall under consolidated billing during an active Part A stay
• Using Type of Bill code 21X instead of 22X on a Part B claim
• Therapy documentation that uses generic templates without objective functional measurements or individualized clinical rationale
• Missing or incorrectly applied KX modifiers when therapy charges exceed the annual threshold
• Billing for maintenance therapy as if it were skilled therapy Medicare Part B covers skilled intervention only
• Failure to track cumulative Part B therapy utilization per beneficiary across the plan year

What this means for your facility: If Part B denial rates are above 5%, run a root cause analysis against these six categories before changing any process. Most Part B billing problems trace back to one or two specific failure points that, once corrected, drive significant improvement across the board.

Ready to Strengthen Your Medicare Part B SNF Billing?

MCA Medical Billing Solutions, L.L.C. manages Medicare Part A and Part B billing for skilled nursing facilities with the expertise to handle eligibility distinctions,consolidated billingrules, and therapy documentation standards that Part B compliance requires.

Contact us for a free billing review. Call (866) 609-5880 or visithttps://mcaskilled.com/.