Final rule will allow more physicians to participate in multiple ACOs


On June 4, 2015, the Centers for Medicare & Medicaid Services (CMS) issued a final rule that revises the Medicare Shared Savings Program (MSSP) regulations relating to accountable care organizations (ACOs). The final rule includes changes that provide increased flexibility for physicians in some specialties to participate in multiple ACOs starting in 2016.


The current MSSP regulations require ACO participants to be exclusive to a single ACO if the participant bills Medicare under any Healthcare Common Procedure Coding System (HCPCS) codes listed in the MSSP definition of “primary care services.” This includes evaluation and management (E/M) CPT codes commonly billed by primary care and specialist physicians.

The final rule revises the Medicare beneficiary assignment methodology by:

  • Excluding services of physician specialists who CMS views as rarely, if ever, providing primary care.
  • Adding transitional care management and chronic care management services to the list of primary care codes.
  • Expanding the consideration of pediatricians, nurse practitioners (NPs), physician assistants (PAs), and certified nurse specialists (CNSs) in the beneficiary assignment process.

The exclusion of various physician specialties in the beneficiary assignment process is particularly significant because it will enhance the ability of physician practices within the excluded specialties (see Table B) to participate in multiple ACOs.

Current regulations

Under the current regulations, primary care physicians and specialists are generally not allowed to participate in multiple ACOs if their services are billed under codes falling within the MSSP definition of “primary care services,” or if the services of other physicians, nurse practitioners, physicians, or clinical nurse specialists at their practice are billed under those codes, which include:

  • 99201 - 99215 (office or outpatient E/M visits)
  • 99304 - 99340 (E/M services in a nursing or similar facility)
  • 99341 - 99350 (E/M services in the home)
  • G0402 (Welcome to Medicare visit)
  • G0438 and G0439 (annual wellness visits)
  • Revenue center codes 0521, 0522, 0524, and 0525 for federally qualified health centers (FQHCs) and rural health centers (RHCs)

These codes are not unique to primary care, despite the label. Physicians have some flexibility to skirt the restriction by contracting with an ACO as a nonparticipant or billing through separate entities—but these approaches require more work and are often overlooked.

CMS uses assignment to identify beneficiaries who have received a sufficient level of primary care service from physicians (and in some cases PAs, NPs, and CNSs) within an ACO to justify designating the ACO as primarily responsible for the patient’s care. This allows the ACO to share in any savings relating to those beneficiaries. Assignment to an ACO is determined under a two-step process:

  • Step 1 – A beneficiary will be assigned to an ACO if the Medicare allowed charges for primary care services furnished to the beneficiary by the ACO’s primary care physicians exceed the Medicare allowed charges for primary care services of primary care physicians who are affiliated with any other ACO or are not affiliated with any ACO.
  • Step 2 – Assignment will be determined under step 2 if a Medicare beneficiary receives primary care services, but does not see a primary care physician. This is similar to step 1 except that the plurality determination is based on Medicare allowed charges for primary care services of physician specialists, NPs, PAs, and CNSs, rather than primary care physicians.

CMS observed in its commentary to the final rule and the proposed rule that approximately 92 percent of the Medicare beneficiaries who are assigned to an ACO are assigned under step 1, with only eight percent assigned under step 2.

What's changing?

The final rule will continue to utilize the existing two-step assignment approach, with modifications that broaden the beneficiary assignment in several respects:

  • By adding CPT codes for transitional care management and chronic care management
  • By including pediatricians, NPs, PAs, and CNSs in step 1 of the assignment process

The modifications also narrow the scope by excluding various physician specialties from the process.

Under this final rule, primary care services of physicians will continue to be included under step 1 of the assignment methodology if the services are furnished by general practice, family practice, internal medicine, or geriatric medicine physicians. Step 1 will be expanded to include primary care services of pediatricians, NPs, PAs, and CNSs.

CMS observed in its commentary that physicians with internal medicine subspecialties frequently provide primary care and sometimes function in a primary care role when treating chronic conditions if the beneficiary does not have a primary care physician. Primary care services billed under the following physician specialty codes will therefore continue to be included in step 2 of the assignment process:

Table A


Cardiology  Endocrinology 
Osteopathic manipulative medicine  Multispecialty clinic or group practice 
Neurology  Addiction medicine 
Obstetrics/gynecology  Hematology 
Sports medicine  Hematology/oncology 
Physical medicine and rehabilitation  Preventive medicine 
Psychiatry  Neuro-psychiatry 
Geriatric psychiatry  Medical oncology 
Pulmonary disease  Gynecology/oncology 

The final rule will narrow beneficiary assignment by excluding the services of physicians within physician specialties that CMS views as rarely, if ever, providing primary care. In particular, the following physician specialty codes will be excluded from step 2 of the beneficiary assignment process:

Table B


General surgery  Pathology  Vascular surgery 
Allergy/immunology Plastic and reconstructive surgery  Cardiac surgery
Otolaryngology  Colorectal surgery  Critical care (intensivists) 
Anesthesiology  Diagnostic radiology  Maxillofacial surgery 
Dermatology  Thoracic surgery  Surgical oncology 
Interventional pain management  Urology  Radiation oncology 
Gastroenterology Nuclear medicine  Emergency medicine 
Neurosurgery Hand surgery  Interventional radiology 
Hospice and palliative care Infectious disease Unknown physician specialty 
Ophthalmology Rheumatology Sleep medicine 
Orthopedic surgery Pain management  Interventional cardiology 
Cardiac electrophysiology  Peripheral vascular disease   

This assignment structure is very similar to the assignment process proposed in December 2014, although some specialties were moved between categories.

The impact on your practice

Under this final rule, physician exclusivity will continue to be linked to beneficiary assignment. Specifically, an ACO participant that submits claims for primary care services that are used to determine beneficiary assignment will be required to be exclusive to one MSSP ACO. Other ACO participants will not.

The revisions to the assignment methodology will give you greater flexibility to participate in multiple ACOs if your physician practice bills only for services of physicians within the specialty codes that are excluded from the assignment process (see specialties listed in Table B above). It is important to keep in mind that even under this final rule, physician exclusivity will continue to be determined at the participant (e.g., practice entity) level. So, if you bill under any of the primary care codes for any of your physicians’ services within any of the step 1 or step 2 specialty codes (e.g., any of the specialties listed in Table A) or for the services of any NP, PA, or CNS, you would not be allowed to participate in multiple ACOs.

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The final rule is available at the Federal Register's website.

For more information, please contact the attorney listed below.

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