Federal Regulations that May Reduce Social Security Benefits
Windfall Elimination Provision
If you work for an employer who does not withhold Social Security taxes from your salary, such as a government agency or an employer in another country, the pension you get based on that work may reduce your Social Security benefits.
Government Pension Offset
If you receive a pension from a federal, state or local government based on work where you did not pay Social Security taxes, the Social Security benefit of your spouse, widow, or widower may be reduced.