20 C.F.R. § 220.175 – Responsibility to notify the Board of events which affect disability.

If the annuitant is entitled to a disability annuity because he or she is disabled for any regular employment, the annuitant should promptly tell the Board if—

(a) His or her impairment(s) improves;
(b) He or she returns to work;
(c) He or she increases the amount of work; or
(d) His or her earnings increase.