ANSWER: Yes. The law allows you to collect your full disability retirement annuity so long as you are not "restored to earning capacity." You are considered "restored to earning capacity" if in any calendar year your earnings from wages, self-employment, or both (but not passive investments) reaches or exceeds 80% of the current rate of basic pay of the position you occupied immediately before retirement. The rule is very strictly construed and you will be stripped of your annuity even if you exceed the 80% ceiling by even a single penny. If you think that you may fall within the scope of this rule, be very sure to find out precisely how it is applied by OPM. For instance, OPM may include in its definition of income, earnings that IRS may exclude from its definition of income.
If you are "restored to earning capacity," you will lose your entire disability retirement annuity, not just some percentage of it. Loss of your annuity will also mean loss of other benefits, including loss of your group health insurance, which will always be more favorable than the individual conversion policy to which you may thereafter be entitled. Persons over 60 years of age are exempt from this 80% earnings limitation.