Here’s one of the less recognized benefits of being a CSRS employee: When you retire you’ll get credit for any unused sick leave in determining your length of service and in the computation of your annuity.

Before 1969, no one got any credit for unused sick leave. After that, they did. How come? Because a study by the U.S. Civil Service Commission revealed that about half of all federal employees had zero sick leave balances when they retired, and the rest had only 352 hours on average; and a follow-up study by the House Post Office and Civil Service Committee found that retiring employees burned up an average of 320 hours in their last year on the job (that’s the equivalent of being too sick to work for a full month in that year). Clearly, something had to be done, and it was. The law was changed. After that, sick leave use plummeted, agencies got the work they were paying for, and employees reaped a benefit for staying on the job.

To understand what that benefit is, you need to know how sick leave is converted into months and years of service when you retire. In short, 2,087 hours equals one year of service. For CSRS retirees that translates into a 2 percent increase in your annuity or, if you have less than a full year of sick leave, 1/6 percent per month.

The exact amount of credit you’ll get depends on whether you have any days of actual service that don’t equal a full month. Any leftover days will be converted to retirement hours and added to those unused sick leave hours. For retirement purposes, all days are 5.797+ hours long, with a month equaling approximately174 hours (that’s the average number of working hours in a month, by this form of math). Any days that don’t add up to a full month are discarded.

While sick leave can be used to increase your annuity, it can’t be used to make you eligible to retire. It can only be added after you have met the age and service requirements to do so. Further, you won’t get any credit for unused sick leave if you leave government before you are eligible to retire and later apply for a deferred annuity. However, if you return to work for the government, those unused hours of sick leave will be restored.