20 CFR 216.16: What is regular non-railroad employment.

(a) Regular non-railroad employment is full or part-time employment for pay.

(b) Regular non-railroad employment does not include any of the following:

(1) Self-employment;

(2) Temporary work provided as relief by an agency of a Federal, State, or local government;

(3) Service inside or outside the United States for an employer under the Railroad Retirement Act, even if the employer does not conduct the main part of its business in the United States;

(4) Involuntary military service not creditable under the Railroad Retirement Act;

(5) Employment with the following agencies of the United States Government:

(i) Department of Transportation;

(ii) Interstate Commerce Commission;

(iii) National Mediation Board;

(iv) Railroad Retirement Board;

(v) National Transportation Safety Board; or

(vi) Surface Transportation Board.

(6) Employment entered into after early retirement by an employee who is receiving an annuity under Conrail's voluntary annuity program. This program is provided under the Staggers Rail Act of 1980 (Pub. L. 96-448); or

(7) Employment with the Alaska Railroad so long as it is an instrumentality of the State of Alaska.