Defining Postdoc Fellows and Associates

What is the difference between a Postdoctoral Associate and a Postdoctoral Fellow?

Postdocs are appointed with the title Postdoctoral Fellow or Postdoctoral Associate depending on the type and source of funding. MIT Policies and Procedures provides detailed descriptions and requirements for postdoctoral associate and postdoctoral fellow appointments.

The MIT title of Postdoctoral Associate applies to those who are paid a salary by MIT. Their salary is usually charged to a grant or contract secured by their faculty mentor.

The MIT title of Postdoctoral Fellow applies to scholars who receive financial support in the form of a fellowship or stipend, usually from an outside agency, either directly or distributed through MIT on behalf of the sponsor. Typically, fellows are responsible for applying for a fellowship award. 

Federal and state laws, tax regulations, and the way MIT benefits are funded create distinctions between Associates and Fellows. An MIT salary is a payment for services paid through MIT’s payroll system, typically with sponsored funds awarded to MIT. Every salary is subject to withholding taxes and Social Security deductions. In addition, for each MIT salary paid to the employee, a “fringe benefit rate” (currently 26% for benefits, plus 9% for vacation) is charged to the same source of funds as the salary. This rate is negotiated annually with the federal government. The funds collected through this mechanism are used to support the costs of employee benefits. In contrast, a Postdoctoral Fellow’s stipend is considered non-salary support, and is not subject to the fringe benefit rate. Different tax regulations also apply. Because fellows do not contribute to the benefits pool and are therefore not eligible for employee benefits, other arrangements are made for comparable provisions whenever possible.

See Benefits for additional information on the differences between Postdoctoral Associates and Postdoctoral Fellows.