Question: Why don’t you ever write about how federal employees can retire on full salary after working only 20 years?

Answer: Because that’s an (especially persistent) urban myth.

Civil service annuities are based on the average of the employee’s highest three consecutive salary years and a multiplier reflecting their years of federal employment.

The Federal Employees Retirement System, covering 95 percent of feds, allows retirement at age 56 with 30 years of service, 60 with 20, or 62 with five. They receive 1 percent of their “high-3” average per year of service, rising to 1.1 percent for those retiring at 62 or later with at least 20 years. For example, someone with 20 years of service and a high-3 average of $80,000 would receive an annual annuity of $16,000 if retiring at age 60 —$17,600 if retiring at 62 or later.

The smaller number of feds under the Civil Service Retirement System don’t get those benefits, but their annuity multiplier is roughly 2 percent per year of service. FERS employees, though, also get Social Security benefits and employer contributions up to 5 percent into the 401(k)-style Thrift Savings Plan.

Various special provisions can apply under both programs, but those are the basics.