Identifying PHI and PII

Electronic forms of Protected Health Information (PHI) and Personally Identifiable Information (PII) must be protected as per federal regulations, and must be encrypted as per the Columbia University's Data Classification,  Registration and Protection of Systems, and Registration and Protection of Endpoints policies. To properly determine what PHI and PII are, we have summarized information from the U.S. Department of Health and Human Services' Guidance Regarding Methods for De-Identification of PHI and Summary of the HIPAA Privacy Rule below.

What is PHI?

Any information transmitted or maintained in any form (i.e. by electronic means, on paper or through oral communication) that relates to the past, present or future physical or mental health or condition of an individual, the provision of health care to an individual or the past, present or future payment for health care and (a) identifies the individual or (b) with respect to which there is a reasonable basis to believe that the information can be used to identify the individual. Identifying characteristics of the identifier are listed below:

PHI 18 Identifiers

  1. Names
  2. All geographic subdivisions smaller than a state, including street address, city, county, precinct, zip code and their equivalent geocodes, except for the initial three digits of a zip code
  3. All elements of dates (except year) directly relating to an individual, including birth date, admission date, discharge date, date of death and all ages over 89 and all elements of dates (including year) indicative of such age, except for ages and elements aggregated into a single category of age 90 or older
  4. Telephone numbers
  5. Fax numbers
  6. Email addresses
  7. Social security numbers
  8. Medical record numbers
  9. Health plan beneficiary numbers
  10. Account numbers
  11. Certificate/license numbers
  12. Vehicle identifiers and serial numbers, including license plate numbers
  13. Device identifiers and serial numbers
  14. Web Universal Resource Locators (URLs)
  15. Internet Protocol (IP) address numbers
  16. Biometric identifiers, including finger prints and voice prints
  17. Full face photographic images or any other comparable images
  18. Any other unique identifying numbers, characteristics or codes (other than unique codes assigned to code the data).


Limited data set is protected health information that excludes the following direct identifiers of the individual or of relatives, employers, or household members of the individual: (1) names; (2) postal address information, other than town or city, State, and zip code; (3) telephone numbers; (4) fax numbers; (5) email addresses; (6) social security numbers; (7) medical record numbers; (8) health plan beneficiary numbers; (9) account numbers; (10) certificate/license plate numbers: (11) vehicle identifiers and serial numbers; (12) device identifiers and serial numbers. (13) web URLs; (14) Internet Protocol (IP) address numbers; (15) biometric identifiers, including fingerprints and voiceprints; and (16) full-face photographic images and any comparable images.
Importantly, unlike de-identified data, protected health information in limited data sets may include the following: city, state and zip codes; all elements of dates (such as admission and discharge dates); and unique codes or identifiers not listed as direct identifiers.

What is PII?

Any information about an individual that could cause harm to such individual, such as medical, financial, employment or criminal records or other information, together with information that can be used to identify or trace an individual's identity, including any other personal information that is linked or linkable to that individual. Examples include social security numbers, driver's license numbers, and credit card numbers.