Senior status is a form of semi-retirement for United States federal judges. To qualify, a judge in the federal court system must be at least 65 years old, served at least 10 years, and the sum of the judge's age and years of service must be at least 80 years. As long as senior judges carry at least a 25 percent caseload or meet other criteria for activity, they remain entitled to maintain a staffed office and chambers, including a secretary and their normal complement of law clerks, and they continue to receive annual cost-of-living increases. The president may appoint new full-time judges to fill the vacancies in full-time judgeships caused by senior status.