20 C.F.R. § 404.1573 : Employees' Benefits — SOCIAL SECURITY ADMINISTRATION — FEDERAL OLD-AGE, SURVIVORS AND DISABILITY INSURANCE (1950- ) — DETERMINING DISABILITY AND BLINDNESS —SUBSTANTIAL GAINFUL ACTIVITY — General information about work activity

(a) The nature of your work. If your duties require use of your experience, skills, supervision and responsibilities, or contribute substantially to the operation of a business, this tends to show that you have the ability to work at the substantial gainful activity level.
(b) How well you perform. We consider how well you do your work when we determine whether or not you are doing substantial gainful activity. If you do your work satisfactorily, this may show that you are working at the substantial gainful activity level. If you are unable, because of your impairments, to do ordinary or simple tasks satisfactorily without more supervision or assistance than is usually given other people doing similar work, this may show that you are not working at the substantial gainful activity level. If you are doing work that involves minimal duties that make little or no demands on you and that are of little or no use to your employer, or to the operation of a business if you are self-employed, this does not show that you are working at the substantial gainful activity level.
(c) If your work is done under special conditions. The work you are doing may be done under special conditions that take into account your impairment, such as work done in a sheltered workshop or as a patient in a hospital. If your work is done under special conditions, we may find that it does not show that you have the ability to do substantial gainful activity. Also, if you are forced to stop or reduce your work because of the removal of special conditions that were related to your impairment and essential to your work, we may find that your work does not show that you are able to do substantial gainful activity. However, work done under special conditions may show that you have the necessary skills and ability to work at the substantial gainful activity level. Examples of the special conditions that may relate to your impairment include, but are not limited to, situations in which-
(1) You required and received special assistance from other employees in performing your work;
(2) You were allowed to work irregular hours or take frequent rest periods;
(3) You were provided with special equipment or were assigned work especially suited to your impairment;
(4) You were able to work only because of specially arranged circumstances, for example, other persons helped you prepare for or get to and from your work;
(5) You were permitted to work at a lower standard of productivity or efficiency than other employees; or
(6) You were given the opportunity to work despite your impairment because of family relationship, past association with your employer, or your employer's concern for your welfare.
(d) If you are self-employed. Supervisory, managerial, advisory or other significant personal services that you perform as a self-employed individual may show that you are able to do substantial gainful activity.
(e) Time spent in work. While the time you spend in work is important, we will not decide whether or not you are doing substantial gainful activity only on that basis. We will still evaluate the work to decide whether it is substantial and gainful regardless of whether you spend more time or less time at the job than workers who are not impaired and who are doing similar work as a regular means of their livelihood.

20 C.F.R. §404.1573

45 FR 55584, 8/20/1980, as amended at 65 FR 42783, 7/11/2000