[Code of Federal Regulations] [Title 20, Volume 1] [Revised as of April 1, 2005] From the U.S. Government Printing Office via GPO Access [CITE: 20CFR220.29] [Page 267] TITLE 20--EMPLOYEES' BENEFITS CHAPTER II--RAILROAD RETIREMENT BOARD PART 220_DETERMINING DISABILITY--Table of Contents Subpart D_Disability Under the Railroad Retirement Act for Any Regular Employment Sec. 220.29 Work that is considered substantial gainful activity. Work is considered to be substantial gainful activity if it-- (a) Involves doing significant and productive physical or mental duties; and (b) Is done or is intended to be done for pay or profit. (See Sec. 220.141 for a detailed explanation of what is substantial gainful activity.)