Code of Federal Regulations Title 5. Administrative Personnel § 5.553.203 Status of individuals serving without reduction

Annuitants reemployed with full salary and annuity under an exception granted in accordance with this part are not considered employees for purposes of subchapter III of chapter 83 or chapter 84 of title 5, United States Code. They may not elect to have retirement contributions withheld from their pay;  they may not use any employment for which an exception is granted as a basis for a supplemental or recomputed annuity;  and they may not participate in the Thrift Savings Plan.