To qualify for disability benefits from Social Security, you must have either a physical or mental impairment that is expected to keep you from doing any substantial work for at least a year or be suffering from a condition that is expected to result in your death. This is a stricter standard than what applies to disability retirement under the CSRS or FERS systems.
If you become disabled, you should file for disability benefits as soon as possible. You can do this by calling or visiting any Social Security office. They will need:

* the names, addresses and phone numbers of your doctors, and of hospitals, clinics, etc., where you have been treated; and

* a summary of where you worked in the last 15 years and the kind of work you did.

Social Security’s disability rules are different from those of private plans or federal retirement. So the fact that you qualify for benefits from FERS does not mean that you will be eligible for Social Security.

If you are applying for a disability benefit under FERS, you must apply for a Social Security disability benefit at the same time.
Generally, your Social Security disability benefits will begin with the sixth full month of your disability. So, for example, if your disabling condition occurred on June 15, you applied for disability two weeks later, and were approved on July 30, your benefits would begin in December.