# National Provider Identifier (NPI)
Source: https://www.stedi.com/docs/healthcare/national-provider-identifier

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title: National Provider Identifier (NPI)
sidebarTitle: "National Provider Identifiers"
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The National Provider Identifier (NPI) is a unique identification number assigned to healthcare providers. It’s used to identify providers in healthcare transactions, like billing, referrals, and insurance claims, and it's required when processing administrative and financial transactions adopted under HIPAA (the Health Insurance Portability and Accountability Act).

If a provider has an NPI, it's required when completing [transaction enrollment](/healthcare/transaction-enrollment) and when sending any healthcare transaction through Stedi, including eligibility checks and claims. In certain rare circumstances, payers may allow providers who don't have an NPI to submit transactions using another identifier, such as their Social Security Number (SSN) instead. Providers who don't have an NPI are typically non-medical providers, such as social workers, home health aides, or transportation services.

In practice, alternative identifiers to the NPI are almost never supported, and using alternative identifiers typically requires a special agreement with the payer. We don't recommend attempting to send an alternative identifier in any transaction unless the payer has explicitly instructed you to do so.

## NPI types

There are two types of NPIs:

* **Type 1 - Individual:** This type of NPI is for individual healthcare providers, such as doctors, dentists, nurse practitioners, physical therapists, and chiropractors. Note that providers who run their own practice likely still need to obtain an individual NPI to use when billing services under their own name.
* **Type 2 - Organization:** This type of NPI is for healthcare organizations or group practices, such as hospitals, clinics, labs, nursing homes, and home health agencies. This type of NPI is used when billing services under the organization’s name, not an individual person. Unlike individual NPIs, a single organization can have multiple organization NPIs for different locations, divisions, or services.

## Find a provider's NPI

You can look up a provider's NPI using the [NPPES NPI Registry](https://npiregistry.cms.hhs.gov/search). The registry allows you to search for NPIs by name, organization, or NPI number. You can also verify the status of an NPI and view the provider's information, including their taxonomy codes and practice locations.

## Generate a dummy NPI

You can generate a dummy NPI for test transactions using this [free online tool](https://jsfiddle.net/alexdresko/cLNB6). Note that these dummy NPIs aren't valid for production transactions.

## Apply for an NPI

You can obtain an NPI from the [National Plan and Provider Enumeration System (NPPES)](https://nppes.cms.hhs.gov/webhelp/nppeshelp/NPPES%20FAQS.html#how-do-i-apply-for-an-npi). The process includes the following steps:

You'll be required to provide the following in your application:

* Personal information, such as your name, address, and phone number
* Type of provider (individual or organization)
* Provider specialty (taxonomy code)
* Practice location and contact information
* Other information, such as your state license number and the name of your state licensing board

Most online applications are processed within 10 business days; paper applications may take longer. Once approved, you'll receive your 10-digit NPI number through email or mail, depending on how you applied.

## NPI format and validation

The NPI is a 10-position, intelligence-free numeric identifier (10-digit number). This means that the numbers do not carry other information about healthcare providers, such as the state in which they live or their medical specialty.

The NPI format consists of 9 numeric digits followed by one numeric check digit. The check digit is calculated using the Luhn formula. When you submit a transaction such as an eligibility check or claim to Stedi, we validate the NPI before submitting it to the upstream payer. At a minimum, we validate that the submitted number passes check digit validation. For example, NPIs in test eligibility checks submitted with a test API key must pass check digit validation. In certain cases, we also validate that the NPI exists in the NPPES database.

### Calculate the check digit manually

Assume the 9-position identifier part of the NPI is 123456789. Using the Luhn formula on the identifier portion, you would calculate the check digit as follows:

1. Double the value of alternate digits, beginning with the rightmost digit:

   2 6 10 14 18

2. Add a constant 24 (to account for the 80840 prefix that would be present on a card issuer identifier), plus the individual digits of the products of doubling, plus unaffected digits:

   24 + 2 + 2 + 6 + 4 + 1 + 0 + 6 + 1 + 4 + 8 + 1 + 8 = 67

3. Subtract the sum from the next higher number ending in zero:

   70 - 67 = 3

The check digit is 3. So, the final NPI with check digit is 1234567893.