PECOS PROVIDER_TYPE vs NPPES NUCC taxonomy disagreement
CMS designated PECOS as the authoritative source for Medicare enrollment under the 2026 verification rules. State Medicaid systems must demonstrate alignment with PECOS, and the window between "discrepancy found" and "enrollment affected" tightens. This finding cross-references each NPI's PECOS PROVIDER_TYPE_CD against its NPPES NUCC taxonomy via the CMS Medicare ↔ NUCC crosswalk. **Result: 508,064 of 1,860,307 comparable pairs (27.31%) show empty intersection between the PECOS-resolved NUCC set and the NPPES-registered NUCC set.** CA leads with 64,180, NY 43,590, TX 39,574, FL 36,190. Every mismatch is a denial-risk flag under the 2026 verification rules — the provider is Medicare-enrolled to bill services their NPPES record does not register them for.
Headline
508,064 of 1,860,307 comparable PPEF-NPPES pairs (27.31%) show a PECOS PROVIDER_TYPE that doesn't resolve to any NUCC code on the NPI's NPPES record, via the CMS Medicare-NUCC crosswalk. Under CMS's 2026 verification rules (PECOS designated as authoritative for Medicare enrollment), this is the regulatorily significant signal: the provider is Medicare-enrolled to bill services their NPPES record does not register them for. Per-state CSVs at /api/v1/states/<state>/h37-pecos-taxonomy-mismatch.csv. The mismatch CSV lists PECOS code(s), resolved-NUCC set, and NPPES-registered NUCC set for every flagged NPI — provider verification + CMS-855 refile is the fix.
508.1K / 1.9M = 27.31%
unit: count
What this means
State Medicaid CMOs
Under the 2026 verification rules your MMIS must align with PECOS. A non-matching taxonomy on a behavioral-health provider does not generate a warning — it generates a denial, then recoupment over the entire window the wrong code was in place. AINPI's per-state CSV gives your PI team the cohort to pre-emptively verify.
Individual providers
PECOS records do not update themselves. If you changed credentialing, switched specialties, or moved from W2 to private practice and did not refile a CMS-855B/I, your PECOS taxonomy is probably wrong. The fix is your responsibility; the cost of a wrong code now is a recoupment letter.
Provider organizations
Run AINPI's per-state list against your roster. Anyone with a PECOS-NPPES taxonomy mismatch is at active denial risk. The 2026 timelines compress the window between flag and enforcement — preemptive cleanup wins.
Null hypothesis
Every Medicare-enrolled NPI in PPEF has a PROVIDER_TYPE that maps cleanly through the CMS Medicare ↔ NUCC taxonomy crosswalk to the NPI's NPPES NUCC taxonomy set. No mismatches at scale.
Denominator
1,860,307 NPIs that are (a) Medicare-enrolled in PPEF (2026-04-01) with a PROVIDER_TYPE_CD that maps through the CMS Medicare ↔ NUCC crosswalk (Oct 2025), AND (b) carry at least one NUCC taxonomy code on their NPPES record. Excludes 2,722 PPEF NPIs with only org-level / non-NUCC PROVIDER_TYPE codes (Part B SUPPLIER - CLINIC/GROUP PRACTICE etc.) and 693,627 PPEF NPIs not found in the NPPES public dataset.
Data source
PPEF × NPPES (`bigquery-public-data.nppes.npi_optimized`) × CMS Medicare Provider and Supplier Taxonomy Crosswalk (loaded to `cms_npd.medicare_taxonomy_crosswalk`, same crosswalk H10–H13 use). Streams PPEF once, joins via NPI, applies the crosswalk in Python; intersection test on the resolved-NUCC sets. See `analysis/h37_pecos_taxonomy.py`.
Notes
The crosswalk is many-to-many: a CMS specialty code can map to multiple NUCC codes (e.g., Internal Medicine spans all IM sub-specialties), and a NUCC code can map to multiple CMS codes. The mismatch test is 'does the PECOS-resolved NUCC set intersect the NPPES set?' — empty intersection is the signal. This is intentionally permissive: a NPI enrolled for Internal Medicine in PECOS but registered as Family Practice in NPPES will register as a match if the crosswalks share any sub-specialty. The mismatch headline is the conservative count. Per-row detail (pecos_resolved_nucc + nppes_nucc columns) shows exactly which code sets are in disagreement for each flagged NPI; CMS-855B/I refile is the fix. Under the 2026 verification rules, every mismatch is a denial-risk flag — behavioral-health especially (see H38 for the subset).