How Medicare pays a skilled nursing facility claim
The bill type decides the method. A 21x claim is a Part A stay, paid as a per diem under the Patient Driven Payment Model (PDPM), never line by line and never by DRG. Each revenue code 0022 line carries a HIPPS code in its HCPCS field and that code's covered days in its units. The per diem is the sum of six components: physical therapy, occupational therapy, speech-language pathology, nursing and non-therapy ancillaries, each the component rate times the case-mix index of the group the HIPPS code names, plus a flat non-case-mix component, all adjusted for the facility's wage index on the labor share.
The day of the stay changes the rate. Physical and occupational therapy pay in full through day 20, then step down 2% every 7 days; non-therapy ancillaries pay 3 times for days 1 to 3. A continuing or last interim bill (213, 214) starts partway through the stay, so the admission date places its days. Each day is priced at the rates and wage index of its own fiscal year, so a September stay billed in October still gets the prior year's rates. Therapy, drugs, supplies and labs on a 21x claim are included under consolidated billing: they carry charges and get no separate payment.
Part B and outpatient SNF claims (22x, 23x) are priced line by line: therapy on the physician fee schedule at the non-facility rate, labs on the clinical lab fee schedule, drugs at the average sales price payment limit. A claim with no bill type whose lines carry no revenue code is not the SNF's claim at all but a physician's professional claim (837P): the facility rate at place of service 31 during a Part A stay, because the SNF's per diem already covers the overhead, and the non-facility rate at 32 otherwise, because no one else covers it. During a Part A stay only the practitioner's professional services are paid on that claim; therapy, labs, drugs, supplies and the technical component of tests are the SNF's. A 21x claim that arrives without revenue codes lost them upstream: it is still the SNF's claim, priced per diem.
Questions
Should the CPT and HCPCS lines on a 21x claim be repriced?
No. They are included in the per diem under consolidated billing. Only the 0022 lines, each a HIPPS code and its days, drive the payment.
Why does an interim bill need the admission date?
Because the variable per diem depends on the day of the stay: therapy steps down after day 20 and the non-therapy ancillary rate is tripled only for days 1 to 3.
What if the claim has no HIPPS code?
Then there is no Medicare-equivalent per diem for those days. The pricer flags them for review, or prices them at a percent of billed charges or at a HIPPS code you supply, whichever fallback you choose. The default code ZZZZZ is different: it is billed for the days an assessment was late, and those days are paid the PDPM default rate, the lowest case-mix group in each component.
What does a physician get for 99305 in a SNF?
The physician fee schedule facility rate when the resident is in a Part A stay (place of service 31), and the non-facility rate at place of service 32. Nationally for CY2026 that is $119.91 and $140.95.