By 
The Centers for Medicare & Medicaid Services (CMS) seeks to collect various data from the appropriate Responsible Reporting Entities (RREs) for the purpose of implementing the mandatory Medicare secondary payer reporting requirements of Section 111 of the MMSEA. This information will be used to make sure Medicare makes the payment in the correct order and/or takes any necessary recovery action.
Under MSP rules, Medicare does not have primary responsibility for paying a Medicare beneficiary’s medical expenses. By law, Medicare is a secondary payer to Group Health Plans (GHP) for certain beneficiaries.
A beneficiary for whom Medicare pays second and Group Health Plans (GHP) pays first is:
1) A Medicare Beneficiary who is age 65 or older and works covered under an employer-sponsored GHP, as a result of being employed by an employer with 20 or more employees (or if it is a multi-employer plan where at least one the employer has 20 or more full-time or part-time employees) OR
2) A Medicare Beneficiary age 65 or older and covered under a working spouse’s employer-sponsored GHP, for an employer with 20 or more employees (working spouse can be any age) (or if a multi-employer plan) where at least one employer has 20 or more full-time or part-time employees) OR
3) A Medicare Beneficiary who has End Stage Renal Disease (ESRD) and is covered by a GHP on any basis. In this case, Medicare pays for the secondary for a 30-month coordination period OR
4) A Medicare Beneficiary who is disabled and covered under his or her own or a family member’s GHP for an employer with 100 or more full-time or part-time employers (or if a multiple employer where at least one employer has 100 or more full-time full-time) or part-time employees.) Based on the previous rules, the onus now falls on employers to provide mandatory reporting of MSP data.