Is intentional underemployment treated differently if the parent has a documented disability?

Yes. A documented disability that genuinely limits a parent's ability to work at their previous level, or at all, is one of the clearest circumstances courts recognize as taking a case outside the usual test for intentional underemployment, since imputing income is meant to address a parent choosing to earn less than they're capable of, not penalizing someone for a genuine incapacity beyond their control. Medical evidence, such as documentation from treating physicians or specialists about functional limitations and prognosis, is generally central to establishing that the reduced earning capacity is real rather than a convenient explanation.

Courts still look at the specific extent of the limitation: a partial disability might still allow for some part-time or modified work, so the analysis can become whether the parent is working to the extent they reasonably can given their condition, rather than a blanket exemption from any income expectation at all. Where a disability is genuine but only partially limiting, a court may still expect the parent to seek accommodated work or apply for available disability benefits rather than doing nothing. Because these cases turn heavily on medical evidence, a parent relying on disability should be prepared to provide credible, specific documentation rather than a general assertion.