PurposeTo optimize the flexibility and relevancy of its Merit-Based Incentive Payment System (MIPS), CMS exempts selected physicians and groups from participation and grants others relaxed reporting requirements. We assess the practical implications of such special status determinations. MethodsFor a random sample of 1,000 Medicare-participating radiologists, the CMS MIPS Participation Lookup Tool was manually searched. Individual radiologists’ and associated groups’ participation requirements and special statuses were assessed. ResultsAlthough only 55% of radiologists were required to participate in MIPS as individuals when considering only one associated taxpayer identification number (TIN), 83% were required to participate as individuals when considering all associated TINs. When using the group reporting option, 97% of radiology groups were required to participate. High participation requirements persisted across generalist and subspecialist radiologists, small and rural, and both academic and nonacademic practices. Non-patient-facing and hospital-based statuses were assigned to high fractions of individual radiologists (91% and 71%, respectively), but much lower fractions of group practices (72% and 25%). Rural and health professional shortage area statuses were assigned to higher percentages of groups (27% and 39%) than individuals (13% and 23%). Small practice status was assigned to 22% of individuals versus 16% of groups. ConclusionAlthough not apparent if only considering individual radiologist-TIN combinations, the overwhelming majority of radiologists will be required to participate in MIPS, at the individual or group level. Radiology groups are strongly encouraged to review their physicians’ MIPS participation requirements and special statuses to ensure optimal performance scores and payment bonuses.