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Medicare NPI Implementation

Guidance for the reporting of legacy numbers assisting Medicare in successfully creating linkages between providers' NPIs and the identifiers that Medicare has assigned to them.


Issued by: Centers for Medicare & Medicaid Services (CMS)

Issue Date: February 11, 2020

The Importance of Reporting Medicare Legacy Numbers in NPPES

The reporting of legacy numbers in the "Other Provider Identifier"/"Other Provider Identifier Type Code" fields in the National Plan and Provider Enumeration System (NPPES) will assist Medicare in successfully creating linkages between providers' NPIs and the identifiers that Medicare has assigned to them (such as PINs).

You should be aware that if you remove your legacy numbers from the "Other Provider Identifier"/"Other Provider Identifier Type Code" fields, linkages that Medicare has established using the reported Medicare legacy numbers will be broken and your Medicare claims could be rejected.

Transcripts from Medicare Fee-For-Service (FFS) Roundtables Available

See the Downloads section below for transcripts form:

  • April 17, 2008 NPI Roundtable
  • February 6, 2008 NPI Roundtable
  • August 2, 2007 Common Billing Errors Roundtable
  • May 10, 2007 Medicare FFS Contingency Plan Roundtable
  • May 14, 2008 NPI Roundtable
  • May 19, 2008 NPI Roundtable, Live Q&A Session

Medicare Expectations on Determination of Subparts

The NPI Final Rule requires health care providers who are organizations and who are covered entities under HIPAA to determine if they have "subparts" that should be assigned NPIs. The NPI Final Rule provides guidance to those health care providers in making those determinations.

We have communicated to the Provider Enrollment staff at the carriers and fiscal intermediaries the Medicare program's expectations concerning the determination of subparts for NPI assignment purposes. We have prepared a document describing the subpart concept and its relationship to the way in which Medicare enrolls its organization providers. This document will be helpful to carrier and fiscal intermediary staff in understanding the issue of subparts and how subpart determination could be done in a way that helps to promote smoother and more efficient Medicare claims processing during the implementation of the NPI in the Medicare program.

The health care industry in general has expressed an interest in being informed of this type of information. We post it here so that it is easily available to interested parties.

HHS is committed to making its websites and documents accessible to the widest possible audience, including individuals with disabilities. We are in the process of retroactively making some documents accessible. If you need assistance accessing an accessible version of this document, please reach out to the

DISCLAIMER: The contents of this database lack the force and effect of law, except as authorized by law (including Medicare Advantage Rate Announcements and Advance Notices) or as specifically incorporated into a contract. The Department may not cite, use, or rely on any guidance that is not posted on the guidance repository, except to establish historical facts.