If you are a University of Colorado Student, you can register on the CITI webpage, adding Your Organization Affiliation as the University of Colorado Denver. If in this process you are asked for an Employee or POI number there, you can enter your Student number and it should work fine.
If you are a University of Colorado Employee, you can do the above and if it is asked for, input your Employee ID number.
If you are an employee of a University of Colorado affiliate (Children's Hospital Colorado, Denver Health Medical Center, University of Colorado Hospital, and the VA Eastern Colorado Health Care System), you may submit this Person of Interest (POI) Information Form, as a part of the process to gain access to the InfoEd eRA research tracking system. Then once you know your POI number, you can register on the CITI webpage, adding Your Organization Affiliation as the University of Colorado Denver, and if asked for it, your POI number.
If you are neither a Student nor an Employee of the University of Colorado or its affiliates, you can still take CITI training by registering on the CITI webpage, adding Your Organization Affiliation as the University of Colorado Denver, and then if asked for an Employee or POI number simply enter any form of ID number you would like. No University sponsorship is necessary for this registration or access. The different types of numbers described above are only needed for some certification tracking and posting purposes.
CITI Course Affiliation and Registration Instructions