Social Security Disability and OWCP

If you become eligible for SSDI benefits while drawing FECA benefits from OWCP, whether for wage loss or a schedule award, there is frequently an offset that will reduce your SSDI benefit. SSA has published documents that explain how the offset is calculated. Keep in mind that attorney fees paid in connection with your receipt of FECA workers' compensation payments from OWCP should be reported to SSA, as this will be used to reduce your offset amount.

http://www.socialsecurity.gov/pubs/10018.html