Guides
Plain-language, source-cited reference guides on NPIs, NPPES, taxonomy codes, NPI validation, and the HHS-OIG exclusion list.
Basics
What Is an NPI Number?
A plain-language explanation of the National Provider Identifier: what it is, who assigns it, what its digits mean, and what it does and does not certify.
Reviewed August 20, 2026
How to Find an NPI Number
Every legitimate way to look up a provider's or organization's NPI, from the official CMS registry to the paperwork a patient already has on hand.
Reviewed August 20, 2026
NPI Type 1 vs Type 2
The difference between an individual (Type 1) and organizational (Type 2) NPI, what each entity type reports to NPPES, and how a provider can end up with both.
Reviewed August 20, 2026
NPPES
What Is NPPES?
NPPES is the federal system that assigns and stores every NPI. Here is what it actually collects, what it publishes, what it withholds, and how often it updates.
Reviewed August 20, 2026
How to Update an NPI Record
How to change an address, name, taxonomy, or other detail on an NPI record in NPPES, the 30-day reporting requirement, and when a paper form is required instead.
Reviewed August 20, 2026
What Does NPI Deactivation Mean?
What it means when an NPI shows as deactivated, what triggers deactivation, whether it can be reactivated, and exactly what the public data does and does not disclose about why.
Reviewed August 20, 2026
Taxonomy
What Are Healthcare Provider Taxonomy Codes?
How the NUCC taxonomy code set describes a provider's specialty, how the ten-character code is structured, and why a taxonomy code is self-reported rather than verified.
Reviewed August 20, 2026
Validation
How Does NPI Number Validation Work?
The exact Luhn check-digit algorithm behind every valid NPI, worked digit by digit against a real enumerated number, plus every way a number can fail format validation.
Reviewed August 20, 2026
Compliance & Exclusions
What Is the OIG Exclusion List?
What the HHS-OIG List of Excluded Individuals/Entities actually prohibits, the difference between mandatory and permissive exclusion, and how reinstatement works.
Reviewed August 20, 2026
Does an NPI Mean a Provider Is Licensed?
No. An NPI is a billing and transaction identifier, not a licensing credential. Here is exactly what NPPES does and does not confirm about a provider.
Reviewed August 20, 2026
OIG Exclusion Screening: What It Is and Who Has to Do It
Why healthcare organizations screen employees and vendors against the HHS-OIG exclusion list, where the requirement comes from, and how far it reaches.
Reviewed August 23, 2026
How to Check OIG Exclusions
The practical steps for checking a person or organization against the HHS-OIG exclusion list, including what to do when you get a possible match on a common name.
Reviewed August 23, 2026
How Often Should You Screen for OIG Exclusions?
Monthly, and the reasoning behind it — where the cadence comes from, what a longer gap actually costs, and when screening more often makes sense.
Reviewed August 23, 2026
OIG LEIE vs. SAM.gov Exclusions
Two federal exclusion lists with different scopes, different publishers and different fields. What each one covers, and why a healthcare organization checks both.
Reviewed August 23, 2026
What Happens If an Employee Is Excluded?
What the payment prohibition actually means for an organization that discovers an excluded employee, and the steps that follow — including self-disclosure.
Reviewed August 23, 2026