What is NPI?
Also called: national provider identifier · NPI number
NPI records are maintained in NPPES and are public. Stale records — an old practice address, a retired taxonomy code — are a quiet and frequent cause of enrollment failures and claim rejections, because payers validate against NPPES.
The taxonomy code attached to an NPI declares specialty, and a mismatch between taxonomy and the services billed will trigger denials on some payer edit sets.
Where Vizora handles this
Primary sources
Where "NPI" is defined by the bodies that set the rules, rather than by us.
- NPI Registry (NPPES) (opens in a new tab)
Centers for Medicare & Medicaid Services — Public lookup and management for National Provider Identifiers. A stale NPPES record is a quietly common cause of enrollment and claim rejections.
- CMS-1500 claim form standards (opens in a new tab)
National Uniform Claim Committee — Maintainer of the CMS-1500 professional claim form and its data element definitions, plus the provider taxonomy code set.
Last reviewed August 20, 2026
Related terms
Credentialing
Credentialing is the verification of a provider's qualifications by a payer, and enrollment is the resulting contract that permits billing under that plan. The process commonly takes 90 to 180 days, and claims for services delivered before the effective date are generally not payable.
CMS-1500
The CMS-1500 is the standard paper claim form used by physicians and non-institutional providers to bill Medicare, Medicaid and most commercial payers. It is maintained by the National Uniform Claim Committee, and its electronic equivalent is the EDI 837P transaction.
Rejection
A rejection is a claim stopped before adjudication — by the clearinghouse or the payer's intake system — for a format, data or eligibility error. Because it never entered adjudication, it carries no appeal rights and does not appear in payer claim status. It must be corrected and resubmitted.
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