Hello, I'm requesting guidance regarding MBI requirements in the following scenarios: 1. Self-pay patients who do not know their Medicare Beneficiary Identifier (MBI) at the time of abstraction or submission. 2. Patients who refuse to provide their MBI despite outreach or standard collection efforts. I know that leaving the MBI field blank results in file rejection. I would appreciate clarification on the appropriate approach in these cases, specifically: • Whether a standardized null value (e.g., Unknown, UNK, or equivalent) is acceptable to allow file acceptance, with the understanding that the case would not be used for measure calculation. • Whether there is a preferred or required value to use in these scenarios to remain compliant with submission specifications. • Any documentation or audit expectations associated with MBI unavailability or patient refusal. Clear guidance on how to handle these situations will help ensure consistency, compliance, and successful file submission. Thank you in advance for your clarification.