Matching RulesAdministrative Restrictions

Administrative Restrictions

Specification v3.4.0, section III.C.6

The following combinations pass the collision threshold but should be administratively restricted:

Candidate combinationP(collision)Secondary risk categoryWhy the risk is not fully captured by P(collision)
Member ID + Payer namespace alone1e-6Above thresholdDoes not meet the 2e-12 threshold and is excluded on that basis, independent of any administrative review.
Subscriber ID + Group Number + Payer namespace~1e-8Data independence risk; recyclability riskGroup number is an employer-level field, not an individual-level field; it provides no incremental individual discrimination and may be shared by hundreds or thousands of members. Group number would transfer to a new member receiving a recycled subscriber ID and therefore provides no recyclability mitigation.