The windfall elimination provision (WEP) is a modified benefit formula designed to remove the unintended advantage, or "windfall," of the regular benefit formula for certain retired or disabled workers who spent less than full careers in covered employment and who are also entitled to pension benefits based on earnings from jobs not covered by Social Security. Background on the Social Security Benefit Formula

Workers qualify for Social Security benefits if they worked and paid Social Security payroll taxes for a sufficient amount of time in covered employment. The Number of People Affected by the WEP

According to the Social Security Administration (SSA), as of December 2018, nearly 1.9 million Social Security beneficiaries were affected by the WEP ( Table 4 ).
The windfall elimination provision (WEP) is a modified benefit formula that reduces the Social Security benefits of certain retired or disabled workers who are also entitled to pension benefits based on earnings from jobs that were not covered by Social Security and thus not subject to the Social Security payroll tax. Its purpose is to remove an unintended advantage or "windfall" that these workers would otherwise receive as a result of the interaction between the regular Social Security benefit formula and the workers' relatively short careers in Social Security-covered employment. In December 2018, nearly 1.9 million people (or about 3% of all Social Security beneficiaries) were affected by the WEP.