A full-time employee for any calendar month is an employee who has on average at least 30 hours of service per week during the calendar month or at least 130 hours of service during the calendar month.

A full-time equivalent employee is a combination of employees, each of whom individually is not a full-time employee, but who, in combination, are equivalent to a full-time employee. An employer determines its number of full-time-equivalent employees for a month in the two steps that follow:

1. Combine the number of hours of service of all non-full-time employees for the month but do not include more than 120 hours of service per employee, and
2. Divide the total by 120.

An employer’s number of full-time equivalent employees (or part-time employees) is only relevant to determining whether an employer is an ALE.  An ALE need not offer minimum essential coverage to its part-time employees to avoid an employer-shared responsibility payment.  A part-time employee’s receipt of the premium tax credit for purchasing coverage through the Marketplace cannot trigger an employer-shared responsibility payment.

for more information on this, visit https://www.irs.gov/affordable-care-act/employers/determining-if-an-employer-is-an-applicable-large-employer