Medicare 101: Navigating the Rules for Coverage and Benefits in Clinical Practice


Medicare, the federal health insurance program established in 1965, serves more than 60 million Americans and made up 21% of total national health expenditures in 2019.1 It is one of the main players in U.S. health policy, supporting a range of efforts to reform payment models and delivery systems. Yet Medicare can leave physicians confused and frustrated about how to deliver high-quality care while adhering to its many rules. This article answers common questions physicians face in navigating patients' Medicare coverage and benefits.


  • The components of the Welcome to Medicare visit, the initial annual wellness visit, and subsequent annual wellness visits can be confusing; see the table of requirements.

  • If you provide other medically necessary services on the same date as a Medicare wellness visit, you can bill for them separately, but explain to patients why you recommend these services and what the out-of-pocket costs are likely to be.

  • Physicians who opt out of Medicare are not prevented from seeing Medicare patients, but neither they nor the patient can bill Medicare for what would otherwise be a covered service.


Eligibility criteria for patients to enroll in Medicare include being 65 or older, receiving at least 24 months of Social Security Disability Insurance benefits or certain Railroad Retirement Board disability benefits, or having specific qualifying conditions such as amyotrophic lateral sclerosis and end-stage renal disease requiring dialysis or a kidney transplant. To enroll in Medicare, an individual must also be either a U.S. citizen, a lawfully present non-citizen with enough work credits to qualify for premium-free Part A, or a lawful permanent resident (green card holder) with five years of continuous residence in the U.S. immediately prior to Medicare enrollment. Individuals who are not lawfully present (undocumented) are ineligible to receive Medicare coverage.

Adults who begin collecting Social Security before they turn 65 are automatically enrolled in Medicare Parts A and B once they meet one of these eligibility criteria. Those who have not yet started collecting Social Security will need to take steps to enroll in Medicare once they are eligible.2



Dr. Hansmann is a family physician and postdoctoral research fellow at the University of Wisconsin School of Medicine and Public Health, Department of Family Medicine and Community Health, Madison, Wisc. Dr. Hansmann's work is supported by a grant from the Health Resources and Services Administration, National Research Service Award (T32HP10010).

Author disclosure: no relevant financial relationships.


show all references

1. NHE Fact Sheet. CMS website. Dec. 16, 2020. Accessed Nov. 17, 2021.

2. Top 5 things you need to know about Medicare enrollment. CMS website. March 23, 2021. Accessed Oct. 12, 2021.

3. Initial preventive physical examination: conditions for and limitations on coverage. 42 CFR §410.16. Accessed Oct. 12, 2021.

4. Goetzel RZ, Staley P, Ogden L, et al. A framework for patient-centered health risk assessments. Centers for Disease Control and Prevention; 2011. Accessed Oct. 12, 2021.

5. Annual wellness visits providing Personalized Prevention Plan Services: conditions for and limitations on coverage. 42 CFR §410.15. Accessed Oct. 12, 2021.

6. Cuenca AE. Making Medicare wellness visits work in practice. Fam Pract Manag. 2012;19(5):11–16.

7. Shay DF. Opting out of Medicare: how to get out and stay out. Fam Pract Manag. 2017;24(6):17–20.


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