FOUO
Are all legacy marked FOUO documents now CUI?

No. It is not an automatic one-to-one swap. Some information previously marked as FOUO will qualify as CUI.  FOUO information must be assessed against the CUI Registry to determine if it is now CUI.  Information previously marked as FOUO does not need to be re-marked as long it remains under DoD control or is accessed online and downloaded for use within the DoD.  However, if the same information is put in a new document or is shared outside the Department, it needs to be assessed to see if it meets the criteria for CUI and marked appropriately.

Not every Executive branch agency has implemented CUI, so you may still receive documents marked as FOUO.  Documents with other markings should be handled in accordance with guidance from those agencies.