What is the test for determining whether a claimant has a severe impairment that significantly limits their ability to do basic work activities?

The Commissioner makes this assessment by employing a five-step analysis outlined in 20 C.F.R. 404.1520. See also Tackett v. Apfel, 180 F.3d 1094, 1098-99 (9th Cir. 1999) (describing five steps). First, the Commissioner determines whether a claimant is engaged in "substantial gainful activity." If so, the claimant is not disabled. 20 C.F.R. 404.1520(b) (2019). Second, the Commissioner determines whether the claimant has a "severe impairment or combination of impairments" that significantly limits the claimant's physical or mental ability to do basic work activities. If not, the claimant is not disabled. Id. 404.1520(c). Third, the medical evidence of the claimant's impairment is compared to a list of impairments that are presumed severe enough to preclude work; if the claimant's impairment meets or equals one of the listed impairments, benefits are awarded. Id. 404.1520(d). If not, the claimant's residual functional capacity is assessed and the evaluation proceeds to step four. Id.

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