Can a health plan replace my identity with a code?

Yes. The federal privacy rule lets a covered entity, such as a health plan, assign a code to records it has de-identified so that only it can re-identify them, provided the code is “not derived from or related to information about the individual” and the plan does not use or disclose the code for any other purpose, or disclose “the mechanism for re-identification” (45 CFR 164.514(c)).