Dennis2 pointed out, somewhat rhetorically,
"For purpose of work deductions" seems taxation related, no?
to which I would say "No, it doesn't seem taxation related" and I would point out that upon reading SSA's Ruling SSR 71-22, I discovered that by its own terms the SSA Ruling asserts that it is
"For purposes of work deductions under section 203 [of the Social Security Act]...." And I know that Section 203 of the Social Security Act has *nothing whatsoever* to do with determining whether income is self-employment income for purposes of Internal Revenue Code Section 1401.
And as pointed out somewhere above in this thread, IRC Section 1402(g) is relatively recent [1996, thank you Dave829] compared to SSA's Ruling 71-22 [1971, I would guess]. Maybe it, the SSA ruling,
was written in a vacuum, and then 25 years later, along came IRC Section 1402(g) which … let oxygen (or whatever) into the vacuum!
[Afterthought: I believe the "work deductions" referred to in the SSA Ruling are the reductions in the amount of money a Social Security retiree is entitled to receive during "retirement" when he or she makes money by working. These aren't "deductions" in the IRS sense, these are *reductions* in the actual Social Security benefits-to-be-paid sense. I sure hope I haven't assumed anything here.
]