From the Hotline: Employee Count for Medicare

Question: How does an employer group calculate the number of full time employees for the purpose of determining if Medicare is primary or secondary? Does the employer group use the calendar year or the medical plan year in running this calculation?

Answer: According to the Centers for Medicare & Medicaid Services, the definition of employee coverage is as follows: “This requirement is met if an employer has 20 or more full-time and/or part time employees for each working day in each of 20 or more calendar weeks in the current or preceding year. Self-employed individuals who participate in an employer plan are not counted as employees in determining if the 20 or more employees requirement is met. Where an employer does not have 20 or more employees in the preceding year, he is required to offer his employees and spouses age 65 or over, primary coverage when he has had 20 or more employees on each working day of 20 calendar weeks of the current year. The employer is then required to offer primary coverage for the remainder of that year and throughout the following year, even if the number of employees subsequently drops below 20. The “20 or more employees” requirement must be met when the individual receives the services for which Medicare benefits are claimed. If at that time, the employer has met the “20 or more employees” requirement in the current year or in the preceding calendar year, the GHP is primary payer. An employer that meets this requirement must provide primary coverage even if less than 20 employees participate in the employer plan.” The full definitions can be found in the CMS regulations at

For more information about Medicare Secondary Payer rules, visit: