POS 31: Skilled Nursing Facility
POS 31 is the place of service code for skilled nursing facility services, used when the resident is in a Medicare Part A covered SNF stay. It pays the facility rate and drags SNF consolidated billing rules onto the claim: many ancillary services must be billed to the SNF, not to Medicare.
- Setting
- SNF resident in a Part A covered stay
- Rate type
- Facility (lower professional payment)
- Common pairing
- Nursing facility E/M 99304-99310
- Watch out for
- Consolidated billing: ancillaries bill the SNF, not Medicare
What does POS 31 mean?
POS 31 identifies a skilled nursing facility: per CMS, a facility that primarily provides inpatient skilled nursing care and related services to patients who require medical, nursing, or rehabilitative services but does not provide the level of care available in a hospital. In Medicare billing practice, POS 31 is used for residents in a Part A covered SNF stay.
The building does not determine the code; the benefit period does. That single fact separates POS 31 from POS 32 and drives most of the denials in this setting. The full code list is in our Place of Service reference.
When do you use POS 31?
Use POS 31 on professional claims for services to a resident during a covered Part A SNF stay:
- Physician and NP/PA visits using nursing facility E/M codes 99304-99310 and discharge codes 99315-99316.
- Psychiatric and psychological services rendered at bedside during the covered stay.
- Podiatry, optometry, and dental visits, subject to consolidated billing exclusions.
Verify the stay status before every visit batch: has the resident used fewer than 100 days, and is the stay still skilled? When Part A ends, flip to POS 32 the next day. Practices that round monthly and code from a stale census list are the ones feeding the denial queue.
How does POS 31 affect payment?
POS 31 pays the Medicare facility rate on professional claims, consistent with every institutional setting: the SNF's per-diem covers overhead, so your claim carries reduced practice expense. The direction matters more than the exact figures: the same clinician effort pays less at POS 31 than a comparable office encounter, and there is no facility fee flowing to you.
The bigger payment force is consolidated billing. During the Part A stay, ancillary services you might normally bill to Medicare (therapy, most diagnostics' technical components, many drugs) are payable only by the SNF. Practices supplying those services need contracts with each facility spelling out rates and invoicing terms, because Medicare will bounce the claim no matter how clean it is. Model your visit economics with the Medicare fee calculator, then decide whether SNF rounding volume justifies the windshield time.
What are the common POS 31 errors and denials?
- CO-109: the consolidated billing denial. The service belongs in the SNF bundle; invoice the facility. Confirm the code meaning in the denial code lookup.
- 31/32 flip errors: billing POS 31 after Part A exhausted (or POS 32 during a covered stay). Payment amount and bundling rules both change, so these come back as denials or reprocessed rates.
- CARC 5: office E/M codes with POS 31 instead of the 99304-99310 family.
- Timely filing casualties: CO-109 denials that sat unworked until the SNF invoicing window and payer timely filing limit both lapsed.
Frequently asked questions
The patient's benefit status, not the building. POS 31 applies when the resident is in a Medicare Part A covered SNF stay (the first up-to-100 days following a qualifying hospital stay). POS 32 applies to nursing facility residents without Part A SNF coverage, including long-term custodial residents and those who exhausted their 100 days. The same bed can be POS 31 in March and POS 32 in April.
During a Part A stay, Medicare pays the SNF a bundled per-diem covering most services the resident receives, so outside suppliers must bill the SNF for included services instead of Medicare. Physician E/M and certain professional services are excluded from the bundle and still bill Medicare directly with POS 31. Therapy, most drugs, labs, and imaging technical components generally bill the SNF.
CO-109 (claim not covered by this payer/contractor) is the signature consolidated billing denial: Medicare is telling you the service belongs in the SNF's bundle. Your remedy is invoicing the SNF under whatever arrangement you have, not appealing Medicare. This is why checking Part A stay status at every date of service, not just at the first visit, is non-negotiable for SNF-facing practices.
The nursing facility family: 99304-99306 for initial care, 99307-99310 for subsequent visits, 99315-99316 for discharge. Office codes 99202-99215 with POS 31 fail CARC 5 edits. Federally mandated visits and medically necessary physician visits both use these codes; the POS stays 31 for the entire covered stay.
Sources & further reading
Reviewed by the ImmediCare Solutions RCM team
Certified billers and coders handling claims across 50+ specialties nationwide. This entry is reviewed against current payer policy and CMS rules. Last review: Jul 5, 2026.
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