Windfall Elimination Provision 

The Windfall Elimination Provision (abbreviated WEP) is a statutory provision in United States law which affects benefits paid by the Social Security Administration under Title II of the Social Security Act. It reduces the Primary Insurance Amount (PIA) of a person's Retirement Insurance Benefits (RIB) or Disability Insurance Benefits (DIB) when that person is eligible or entitled to a pension based on a job which did not contribute to the Social Security Trust Fund. While in effect, it also affects the benefits of others claiming on the same social security record.

 Government Pension Offset

The Government Pension Offset is a statutory provision in United States law which affects benefits paid by the Social Security Administration. It reduces spousal Social Security retirement benefits in situations where the worker did not pay Social Security tax. (Many state and local government employees do not contribute to the Social Security system.) This is in contrast to the Windfall Elimination Provision, which reduces Social Security benefits of the worker.