I am attempting to access my OER for 2022. It is not posted in IPERMS or EES. Where else can I access previous OERs?

It's not posted in EES? Did you have a manual OER created and sent to HRC because you were in a unique situation? That should be the only reason it wouldn't be in EES if it was done.

You could try "My AC Record" on eMILPO*, but if it's not showing up in EES or iPERMS, then it's probably not there either.

I would call the Evaluation Processing Office* to see if the OER was ever processed.
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* My AC Record - https://federation.eams.army.mil/pool/sso/authenticate/l/2?m=GET&r=t&u=https%3A%2F%2Femilpo.ahrs.army.mil%2F
* Evaluations Selections and Promotions POCs - https://www.hrc.army.mil/content/Evaluations%20Selections%20and%20Promotions%20POCs

I think that I remember that I always received a copy of mine. Check your files. You should keep every scrap of paper that you get. When you ETS or Retire, latch on to your Field 201 and Health Record (both tan) and your finance file (green).